ManpageΒΆ

This is simply a copy of what you should see on running man mlr at a command prompt, once Miller is installed on your system.

MILLER(1)                                                        MILLER(1)



NAME
       miller - like awk, sed, cut, join, and sort for name-indexed data such
       as CSV and tabular JSON.

SYNOPSIS
       Usage: mlr [I/O options] {verb} [verb-dependent options ...] {zero or
       more file names}


DESCRIPTION
       Miller operates on key-value-pair data while the familiar Unix tools
       operate on integer-indexed fields: if the natural data structure for
       the latter is the array, then Miller's natural data structure is the
       insertion-ordered hash map.  This encompasses a variety of data
       formats, including but not limited to the familiar CSV, TSV, and JSON.
       (Miller can handle positionally-indexed data as a special case.) This
       manpage documents Miller v5.9.1-dev.

EXAMPLES
   COMMAND-LINE SYNTAX
       mlr --csv cut -f hostname,uptime mydata.csv
       mlr --tsv --rs lf filter '$status != "down" && $upsec >= 10000' *.tsv
       mlr --nidx put '$sum = $7 < 0.0 ? 3.5 : $7 + 2.1*$8' *.dat
       grep -v '^#' /etc/group | mlr --ifs : --nidx --opprint label group,pass,gid,member then sort -f group
       mlr join -j account_id -f accounts.dat then group-by account_name balances.dat
       mlr --json put '$attr = sub($attr, "([0-9]+)_([0-9]+)_.*", "\1:\2")' data/*.json
       mlr stats1 -a min,mean,max,p10,p50,p90 -f flag,u,v data/*
       mlr stats2 -a linreg-pca -f u,v -g shape data/*
       mlr put -q '@sum[$a][$b] += $x; end {emit @sum, "a", "b"}' data/*
       mlr --from estimates.tbl put '
     for (k,v in $*) {
       if (is_numeric(v) && k =~ "^[t-z].*$") {
         $sum += v; $count += 1
       }
     }
     $mean = $sum / $count # no assignment if count unset'
       mlr --from infile.dat put -f analyze.mlr
       mlr --from infile.dat put 'tee > "./taps/data-".$a."-".$b, $*'
       mlr --from infile.dat put 'tee | "gzip > ./taps/data-".$a."-".$b.".gz", $*'
       mlr --from infile.dat put -q '@v=$*; dump | "jq .[]"'
       mlr --from infile.dat put  '(NR % 1000 == 0) { print > stderr, "Checkpoint ".NR}'

   DATA FORMATS
     DKVP: delimited key-value pairs (Miller default format)
     +---------------------+
     | apple=1,bat=2,cog=3 | Record 1: "apple" => "1", "bat" => "2", "cog" => "3"
     | dish=7,egg=8,flint  | Record 2: "dish" => "7", "egg" => "8", "3" => "flint"
     +---------------------+

     NIDX: implicitly numerically indexed (Unix-toolkit style)
     +---------------------+
     | the quick brown     | Record 1: "1" => "the", "2" => "quick", "3" => "brown"
     | fox jumped          | Record 2: "1" => "fox", "2" => "jumped"
     +---------------------+

     CSV/CSV-lite: comma-separated values with separate header line
     +---------------------+
     | apple,bat,cog       |
     | 1,2,3               | Record 1: "apple => "1", "bat" => "2", "cog" => "3"
     | 4,5,6               | Record 2: "apple" => "4", "bat" => "5", "cog" => "6"
     +---------------------+

     Tabular JSON: nested objects are supported, although arrays within them are not:
     +---------------------+
     | {                   |
     |  "apple": 1,        | Record 1: "apple" => "1", "bat" => "2", "cog" => "3"
     |  "bat": 2,          |
     |  "cog": 3           |
     | }                   |
     | {                   |
     |   "dish": {         | Record 2: "dish:egg" => "7", "dish:flint" => "8", "garlic" => ""
     |     "egg": 7,       |
     |     "flint": 8      |
     |   },                |
     |   "garlic": ""      |
     | }                   |
     +---------------------+

     PPRINT: pretty-printed tabular
     +---------------------+
     | apple bat cog       |
     | 1     2   3         | Record 1: "apple => "1", "bat" => "2", "cog" => "3"
     | 4     5   6         | Record 2: "apple" => "4", "bat" => "5", "cog" => "6"
     +---------------------+

     XTAB: pretty-printed transposed tabular
     +---------------------+
     | apple 1             | Record 1: "apple" => "1", "bat" => "2", "cog" => "3"
     | bat   2             |
     | cog   3             |
     |                     |
     | dish 7              | Record 2: "dish" => "7", "egg" => "8"
     | egg  8              |
     +---------------------+

     Markdown tabular (supported for output only):
     +-----------------------+
     | | apple | bat | cog | |
     | | ---   | --- | --- | |
     | | 1     | 2   | 3   | | Record 1: "apple => "1", "bat" => "2", "cog" => "3"
     | | 4     | 5   | 6   | | Record 2: "apple" => "4", "bat" => "5", "cog" => "6"
     +-----------------------+

OPTIONS
       In the following option flags, the version with "i" designates the
       input stream, "o" the output stream, and the version without prefix
       sets the option for both input and output stream. For example: --irs
       sets the input record separator, --ors the output record separator, and
       --rs sets both the input and output separator to the given value.

   HELP OPTIONS
     -h or --help                 Show this message.
     --version                    Show the software version.
     {verb name} --help           Show verb-specific help.
     --help-all-verbs             Show help on all verbs.
     -l or --list-all-verbs       List only verb names.
     -L                           List only verb names, one per line.
     -f or --help-all-functions   Show help on all built-in functions.
     -F                           Show a bare listing of built-in functions by name.
     -k or --help-all-keywords    Show help on all keywords.
     -K                           Show a bare listing of keywords by name.

   VERB LIST
    altkv bar bootstrap cat check clean-whitespace count count-distinct
    count-similar cut decimate fill-down filter format-values fraction grep
    group-by group-like having-fields head histogram join label least-frequent
    merge-fields most-frequent nest nothing put regularize remove-empty-columns
    rename reorder repeat reshape sample sec2gmt sec2gmtdate seqgen shuffle
    skip-trivial-records sort stats1 stats2 step tac tail tee top uniq unsparsify

   FUNCTION LIST
    + + - - * / // .+ .+ .- .- .* ./ .// % ** | ^ & ~ << >> bitcount == != =~ !=~
    > >= < <= && || ^^ ! ? : . gsub regextract regextract_or_else strlen sub ssub
    substr tolower toupper capitalize lstrip rstrip strip collapse_whitespace
    clean_whitespace system abs acos acosh asin asinh atan atan2 atanh cbrt ceil
    cos cosh erf erfc exp expm1 floor invqnorm log log10 log1p logifit madd max
    mexp min mmul msub pow qnorm round roundm sgn sin sinh sqrt tan tanh urand
    urandrange urand32 urandint dhms2fsec dhms2sec fsec2dhms fsec2hms gmt2sec
    localtime2sec hms2fsec hms2sec sec2dhms sec2gmt sec2gmt sec2gmtdate
    sec2localtime sec2localtime sec2localdate sec2hms strftime strftime_local
    strptime strptime_local systime is_absent is_bool is_boolean is_empty
    is_empty_map is_float is_int is_map is_nonempty_map is_not_empty is_not_map
    is_not_null is_null is_numeric is_present is_string asserting_absent
    asserting_bool asserting_boolean asserting_empty asserting_empty_map
    asserting_float asserting_int asserting_map asserting_nonempty_map
    asserting_not_empty asserting_not_map asserting_not_null asserting_null
    asserting_numeric asserting_present asserting_string boolean float fmtnum
    hexfmt int string typeof depth haskey joink joinkv joinv leafcount length
    mapdiff mapexcept mapselect mapsum splitkv splitkvx splitnv splitnvx

       Please use "mlr --help-function {function name}" for function-specific help.

   I/O FORMATTING
     --idkvp   --odkvp   --dkvp      Delimited key-value pairs, e.g "a=1,b=2"
                                     (this is Miller's default format).

     --inidx   --onidx   --nidx      Implicitly-integer-indexed fields
                                     (Unix-toolkit style).
     -T                              Synonymous with "--nidx --fs tab".

     --icsv    --ocsv    --csv       Comma-separated value (or tab-separated
                                     with --fs tab, etc.)

     --itsv    --otsv    --tsv       Keystroke-savers for "--icsv --ifs tab",
                                     "--ocsv --ofs tab", "--csv --fs tab".
     --iasv    --oasv    --asv       Similar but using ASCII FS 0x1f and RS 0x1e
     --iusv    --ousv    --usv       Similar but using Unicode FS U+241F (UTF-8 0xe2909f)
                                     and RS U+241E (UTF-8 0xe2909e)

     --icsvlite --ocsvlite --csvlite Comma-separated value (or tab-separated
                                     with --fs tab, etc.). The 'lite' CSV does not handle
                                     RFC-CSV double-quoting rules; is slightly faster;
                                     and handles heterogeneity in the input stream via
                                     empty newline followed by new header line. See also
                                     http://johnkerl.org/miller/doc/file-formats.html#CSV/TSV/etc.

     --itsvlite --otsvlite --tsvlite Keystroke-savers for "--icsvlite --ifs tab",
                                     "--ocsvlite --ofs tab", "--csvlite --fs tab".
     -t                              Synonymous with --tsvlite.
     --iasvlite --oasvlite --asvlite Similar to --itsvlite et al. but using ASCII FS 0x1f and RS 0x1e
     --iusvlite --ousvlite --usvlite Similar to --itsvlite et al. but using Unicode FS U+241F (UTF-8 0xe2909f)
                                     and RS U+241E (UTF-8 0xe2909e)

     --ipprint --opprint --pprint    Pretty-printed tabular (produces no
                                     output until all input is in).
                         --right     Right-justifies all fields for PPRINT output.
                         --barred    Prints a border around PPRINT output
                                     (only available for output).

               --omd                 Markdown-tabular (only available for output).

     --ixtab   --oxtab   --xtab      Pretty-printed vertical-tabular.
                         --xvright   Right-justifies values for XTAB format.

     --ijson   --ojson   --json      JSON tabular: sequence or list of one-level
                                     maps: {...}{...} or [{...},{...}].
       --json-map-arrays-on-input    JSON arrays are unmillerable. --json-map-arrays-on-input
       --json-skip-arrays-on-input   is the default: arrays are converted to integer-indexed
       --json-fatal-arrays-on-input  maps. The other two options cause them to be skipped, or
                                     to be treated as errors.  Please use the jq tool for full
                                     JSON (pre)processing.
                         --jvstack   Put one key-value pair per line for JSON
                                     output.
                   --jsonx --ojsonx  Keystroke-savers for --json --jvstack
                   --jsonx --ojsonx  and --ojson --jvstack, respectively.
                         --jlistwrap Wrap JSON output in outermost [ ].
                       --jknquoteint Do not quote non-string map keys in JSON output.
                        --jvquoteall Quote map values in JSON output, even if they're
                                     numeric.
                 --jflatsep {string} Separator for flattening multi-level JSON keys,
                                     e.g. '{"a":{"b":3}}' becomes a:b => 3 for
                                     non-JSON formats. Defaults to :.

     -p is a keystroke-saver for --nidx --fs space --repifs

     Examples: --csv for CSV-formatted input and output; --idkvp --opprint for
     DKVP-formatted input and pretty-printed output.

     Please use --iformat1 --oformat2 rather than --format1 --oformat2.
     The latter sets up input and output flags for format1, not all of which
     are overridden in all cases by setting output format to format2.

   COMMENTS IN DATA
     --skip-comments                 Ignore commented lines (prefixed by "#")
                                     within the input.
     --skip-comments-with {string}   Ignore commented lines within input, with
                                     specified prefix.
     --pass-comments                 Immediately print commented lines (prefixed by "#")
                                     within the input.
     --pass-comments-with {string}   Immediately print commented lines within input, with
                                     specified prefix.
       Notes:
       * Comments are only honored at the start of a line.
       * In the absence of any of the above four options, comments are data like
     any other text.
       * When pass-comments is used, comment lines are written to standard output
     immediately upon being read; they are not part of the record stream.
     Results may be counterintuitive. A suggestion is to place comments at the
     start of data files.

   FORMAT-CONVERSION KEYSTROKE-SAVERS
       As keystroke-savers for format-conversion you may use the following:
           --c2t --c2d --c2n --c2j --c2x --c2p --c2m
     --t2c       --t2d --t2n --t2j --t2x --t2p --t2m
     --d2c --d2t       --d2n --d2j --d2x --d2p --d2m
     --n2c --n2t --n2d       --n2j --n2x --n2p --n2m
     --j2c --j2t --j2d --j2n       --j2x --j2p --j2m
     --x2c --x2t --x2d --x2n --x2j       --x2p --x2m
     --p2c --p2t --p2d --p2n --p2j --p2x       --p2m
       The letters c t d n j x p m refer to formats CSV, TSV, DKVP, NIDX, JSON, XTAB,
       PPRINT, and markdown, respectively. Note that markdown format is available for
       output only.

   COMPRESSED I/O
     --prepipe {command} This allows Miller to handle compressed inputs. You can do
     without this for single input files, e.g. "gunzip < myfile.csv.gz | mlr ...".

     However, when multiple input files are present, between-file separations are
     lost; also, the FILENAME variable doesn't iterate. Using --prepipe you can
     specify an action to be taken on each input file. This pre-pipe command must
     be able to read from standard input; it will be invoked with
       {command} < {filename}.
     Examples:
       mlr --prepipe 'gunzip'
       mlr --prepipe 'zcat -cf'
       mlr --prepipe 'xz -cd'
       mlr --prepipe cat
       mlr --prepipe-gunzip
       mlr --prepipe-zcat
     Note that this feature is quite general and is not limited to decompression
     utilities. You can use it to apply per-file filters of your choice.
     For output compression (or other) utilities, simply pipe the output:
       mlr ... | {your compression command}

     There are shorthands --prepipe-zcat and --prepipe-gunzip which are
     valid in .mlrrc files. The --prepipe flag is not valid in .mlrrc
     files since that would put execution of the prepipe command under
     control of the .mlrrc file.

   SEPARATORS
     --rs     --irs     --ors              Record separators, e.g. 'lf' or '\r\n'
     --fs     --ifs     --ofs  --repifs    Field separators, e.g. comma
     --ps     --ips     --ops              Pair separators, e.g. equals sign

     Notes about line endings:
     * Default line endings (--irs and --ors) are "auto" which means autodetect from
       the input file format, as long as the input file(s) have lines ending in either
       LF (also known as linefeed, '\n', 0x0a, Unix-style) or CRLF (also known as
       carriage-return/linefeed pairs, '\r\n', 0x0d 0x0a, Windows style).
     * If both irs and ors are auto (which is the default) then LF input will lead to LF
       output and CRLF input will lead to CRLF output, regardless of the platform you're
       running on.
     * The line-ending autodetector triggers on the first line ending detected in the input
       stream. E.g. if you specify a CRLF-terminated file on the command line followed by an
       LF-terminated file then autodetected line endings will be CRLF.
     * If you use --ors {something else} with (default or explicitly specified) --irs auto
       then line endings are autodetected on input and set to what you specify on output.
     * If you use --irs {something else} with (default or explicitly specified) --ors auto
       then the output line endings used are LF on Unix/Linux/BSD/MacOSX, and CRLF on Windows.

     Notes about all other separators:
     * IPS/OPS are only used for DKVP and XTAB formats, since only in these formats
       do key-value pairs appear juxtaposed.
     * IRS/ORS are ignored for XTAB format. Nominally IFS and OFS are newlines;
       XTAB records are separated by two or more consecutive IFS/OFS -- i.e.
       a blank line. Everything above about --irs/--ors/--rs auto becomes --ifs/--ofs/--fs
       auto for XTAB format. (XTAB's default IFS/OFS are "auto".)
     * OFS must be single-character for PPRINT format. This is because it is used
       with repetition for alignment; multi-character separators would make
       alignment impossible.
     * OPS may be multi-character for XTAB format, in which case alignment is
       disabled.
     * TSV is simply CSV using tab as field separator ("--fs tab").
     * FS/PS are ignored for markdown format; RS is used.
     * All FS and PS options are ignored for JSON format, since they are not relevant
       to the JSON format.
     * You can specify separators in any of the following ways, shown by example:
       - Type them out, quoting as necessary for shell escapes, e.g.
         "--fs '|' --ips :"
       - C-style escape sequences, e.g. "--rs '\r\n' --fs '\t'".
       - To avoid backslashing, you can use any of the following names:
         cr crcr newline lf lflf crlf crlfcrlf tab space comma pipe slash colon semicolon equals
     * Default separators by format:
         File format  RS       FS       PS
         gen          N/A      (N/A)    (N/A)
         dkvp         auto     ,        =
         json         auto     (N/A)    (N/A)
         nidx         auto     space    (N/A)
         csv          auto     ,        (N/A)
         csvlite      auto     ,        (N/A)
         markdown     auto     (N/A)    (N/A)
         pprint       auto     space    (N/A)
         xtab         (N/A)    auto     space

   CSV-SPECIFIC OPTIONS
     --implicit-csv-header Use 1,2,3,... as field labels, rather than from line 1
                        of input files. Tip: combine with "label" to recreate
                        missing headers.
     --allow-ragged-csv-input|--ragged If a data line has fewer fields than the header line,
                        fill remaining keys with empty string. If a data line has more
                        fields than the header line, use integer field labels as in
                        the implicit-header case.
     --headerless-csv-output   Print only CSV data lines.
     -N                 Keystroke-saver for --implicit-csv-header --headerless-csv-output.

   DOUBLE-QUOTING FOR CSV/CSVLITE OUTPUT
     --quote-all        Wrap all fields in double quotes
     --quote-none       Do not wrap any fields in double quotes, even if they have
                        OFS or ORS in them
     --quote-minimal    Wrap fields in double quotes only if they have OFS or ORS
                        in them (default)
     --quote-numeric    Wrap fields in double quotes only if they have numbers
                        in them
     --quote-original   Wrap fields in double quotes if and only if they were
                        quoted on input. This isn't sticky for computed fields:
                        e.g. if fields a and b were quoted on input and you do
                        "put '$c = $a . $b'" then field c won't inherit a or b's
                        was-quoted-on-input flag.

   NUMERICAL FORMATTING
     --ofmt {format}    E.g. %.18lf, %.0lf. Please use sprintf-style codes for
                        double-precision. Applies to verbs which compute new
                        values, e.g. put, stats1, stats2. See also the fmtnum
                        function within mlr put (mlr --help-all-functions).
                        Defaults to %lf.

   OTHER OPTIONS
     --seed {n} with n of the form 12345678 or 0xcafefeed. For put/filter
                        urand()/urandint()/urand32().
     --nr-progress-mod {m}, with m a positive integer: print filename and record
                        count to stderr every m input records.
     --from {filename}  Use this to specify an input file before the verb(s),
                        rather than after. May be used more than once. Example:
                        "mlr --from a.dat --from b.dat cat" is the same as
                        "mlr cat a.dat b.dat".
     -n                 Process no input files, nor standard input either. Useful
                        for mlr put with begin/end statements only. (Same as --from
                        /dev/null.) Also useful in "mlr -n put -v '...'" for
                        analyzing abstract syntax trees (if that's your thing).
     -I                 Process files in-place. For each file name on the command
                        line, output is written to a temp file in the same
                        directory, which is then renamed over the original. Each
                        file is processed in isolation: if the output format is
                        CSV, CSV headers will be present in each output file;
                        statistics are only over each file's own records; and so on.

   THEN-CHAINING
       Output of one verb may be chained as input to another using "then", e.g.
     mlr stats1 -a min,mean,max -f flag,u,v -g color then sort -f color

   AUXILIARY COMMANDS
       Miller has a few otherwise-standalone executables packaged within it.
       They do not participate in any other parts of Miller.
       Available subcommands:
     aux-list
     lecat
     termcvt
     hex
     unhex
     netbsd-strptime
       For more information, please invoke mlr {subcommand} --help

MLRRC
       You can set up personal defaults via a $HOME/.mlrrc and/or ./.mlrrc.
       For example, if you usually process CSV, then you can put "--csv" in your .mlrrc file
       and that will be the default input/output format unless otherwise specified on the command line.

       The .mlrrc file format is one "--flag" or "--option value" per line, with the leading "--" optional.
       Hash-style comments and blank lines are ignored.

       Sample .mlrrc:
       # Input and output formats are CSV by default (unless otherwise specified
       # on the mlr command line):
       csv
       # These are no-ops for CSV, but when I do use JSON output, I want these
       # pretty-printing options to be used:
       jvstack
       jlistwrap

       How to specify location of .mlrrc:
       * If $MLRRC is set:
     o If its value is "__none__" then no .mlrrc files are processed.
     o Otherwise, its value (as a filename) is loaded and processed. If there are syntax
       errors, they abort mlr with a usage message (as if you had mistyped something on the
       command line). If the file can't be loaded at all, though, it is silently skipped.
     o Any .mlrrc in your home directory or current directory is ignored whenever $MLRRC is
       set in the environment.
       * Otherwise:
     o If $HOME/.mlrrc exists, it's then processed as above.
     o If ./.mlrrc exists, it's then also processed as above.
     (I.e. current-directory .mlrrc defaults are stacked over home-directory .mlrrc defaults.)

       See also:
       https://johnkerl.org/miller/doc/customization.html

VERBS
   altkv
       Usage: mlr altkv [no options]
       Given fields with values of the form a,b,c,d,e,f emits a=b,c=d,e=f pairs.

   bar
       Usage: mlr bar [options]
       Replaces a numeric field with a number of asterisks, allowing for cheesy
       bar plots. These align best with --opprint or --oxtab output format.
       Options:
       -f   {a,b,c}  Field names to convert to bars.
       -c   {character}  Fill character: default '*'.
       -x   {character}  Out-of-bounds character: default '#'.
       -b   {character}  Blank character: default '.'.
       --lo {lo}     Lower-limit value for min-width bar: default '0.000000'.
       --hi {hi}     Upper-limit value for max-width bar: default '100.000000'.
       -w   {n}      Bar-field width: default '40'.
       --auto                Automatically computes limits, ignoring --lo and --hi.
                     Holds all records in memory before producing any output.

   bootstrap
       Usage: mlr bootstrap [options]
       Emits an n-sample, with replacement, of the input records.
       Options:
       -n {number} Number of samples to output. Defaults to number of input records.
               Must be non-negative.
       See also mlr sample and mlr shuffle.

   cat
       Usage: mlr cat [options]
       Passes input records directly to output. Most useful for format conversion.
       Options:
       -n    Prepend field "n" to each record with record-counter starting at 1
       -g {comma-separated field name(s)} When used with -n/-N, writes record-counters
             keyed by specified field name(s).
       -v    Write a low-level record-structure dump to stderr.
       -N {name} Prepend field {name} to each record with record-counter starting at 1

   check
       Usage: mlr check
       Consumes records without printing any output.
       Useful for doing a well-formatted check on input data.

   clean-whitespace
       Usage: mlr clean-whitespace [options] {old1,new1,old2,new2,...}
       For each record, for each field in the record, whitespace-cleans the keys and
       values. Whitespace-cleaning entails stripping leading and trailing whitespace,
       and replacing multiple whitespace with singles. For finer-grained control,
       please see the DSL functions lstrip, rstrip, strip, collapse_whitespace,
       and clean_whitespace.

       Options:
       -k|--keys-only        Do not touch values.
       -v|--values-only  Do not touch keys.
       It is an error to specify -k as well as -v.

   count
       Usage: mlr count [options]
       Prints number of records, optionally grouped by distinct values for specified field names.

       Options:
       -g {a,b,c}    Field names for distinct count.
       -n        Show only the number of distinct values. Not interesting without -g.
       -o {name}     Field name for output count. Default "count".

   count-distinct
       Usage: mlr count-distinct [options]
       Prints number of records having distinct values for specified field names.
       Same as uniq -c.

       Options:
       -f {a,b,c}    Field names for distinct count.
       -n        Show only the number of distinct values. Not compatible with -u.
       -o {name}     Field name for output count. Default "count".
                 Ignored with -u.
       -u        Do unlashed counts for multiple field names. With -f a,b and
                 without -u, computes counts for distinct combinations of a
                 and b field values. With -f a,b and with -u, computes counts
                 for distinct a field values and counts for distinct b field
                 values separately.

   count-similar
       Usage: mlr count-similar [options]
       Ingests all records, then emits each record augmented by a count of
       the number of other records having the same group-by field values.
       Options:
       -g {d,e,f} Group-by-field names for counts.
       -o {name}  Field name for output count. Default "count".

   cut
       Usage: mlr cut [options]
       Passes through input records with specified fields included/excluded.
       -f {a,b,c}   Field names to include for cut.
       -o           Retain fields in the order specified here in the argument list.
                    Default is to retain them in the order found in the input data.
       -x|--complement      Exclude, rather than include, field names specified by -f.
       -r           Treat field names as regular expressions. "ab", "a.*b" will
                    match any field name containing the substring "ab" or matching
                    "a.*b", respectively; anchors of the form "^ab$", "^a.*b$" may
                    be used. The -o flag is ignored when -r is present.
       Examples:
     mlr cut -f hostname,status
     mlr cut -x -f hostname,status
     mlr cut -r -f '^status$,sda[0-9]'
     mlr cut -r -f '^status$,"sda[0-9]"'
     mlr cut -r -f '^status$,"sda[0-9]"i' (this is case-insensitive)

   decimate
       Usage: mlr decimate [options]
       -n {count}    Decimation factor; default 10
       -b        Decimate by printing first of every n.
       -e        Decimate by printing last of every n (default).
       -g {a,b,c}    Optional group-by-field names for decimate counts
       Passes through one of every n records, optionally by category.

   fill-down
       Usage: mlr fill-down [options]
       -f {a,b,c}      Field names for fill-down
       -a|--only-if-absent Field names for fill-down
       If a given record has a missing value for a given field, fill that from
       the corresponding value from a previous record, if any.
       By default, a 'missing' field either is absent, or has the empty-string value.
       With -a, a field is 'missing' only if it is absent.

   filter
       Usage: mlr filter [options] {expression}
       Prints records for which {expression} evaluates to true.
       If there are multiple semicolon-delimited expressions, all of them are
       evaluated and the last one is used as the filter criterion.

       Conversion options:
       -S: Keeps field values as strings with no type inference to int or float.
       -F: Keeps field values as strings or floats with no inference to int.
       All field values are type-inferred to int/float/string unless this behavior is
       suppressed with -S or -F.

       Output/formatting options:
       --oflatsep {string}: Separator to use when flattening multi-level @-variables
       to output records for emit. Default ":".
       --jknquoteint: For dump output (JSON-formatted), do not quote map keys if non-string.
       --jvquoteall: For dump output (JSON-formatted), quote map values even if non-string.
       Any of the output-format command-line flags (see mlr -h). Example: using
     mlr --icsv --opprint ... then put --ojson 'tee > "mytap-".$a.".dat", $*' then ...
       the input is CSV, the output is pretty-print tabular, but the tee-file output
       is written in JSON format.
       --no-fflush: for emit, tee, print, and dump, don't call fflush() after every
       record.

       Expression-specification options:
       -f {filename}: the DSL expression is taken from the specified file rather
       than from the command line. Outer single quotes wrapping the expression
       should not be placed in the file. If -f is specified more than once,
       all input files specified using -f are concatenated to produce the expression.
       (For example, you can define functions in one file and call them from another.)
       -e {expression}: You can use this after -f to add an expression. Example use
       case: define functions/subroutines in a file you specify with -f, then call
       them with an expression you specify with -e.
       (If you mix -e and -f then the expressions are evaluated in the order encountered.
       Since the expression pieces are simply concatenated, please be sure to use intervening
       semicolons to separate expressions.)

       -s name=value: Predefines out-of-stream variable @name to have value "value".
       Thus mlr filter put -s foo=97 '$column += @foo' is like
       mlr filter put 'begin {@foo = 97} $column += @foo'.
       The value part is subject to type-inferencing as specified by -S/-F.
       May be specified more than once, e.g. -s name1=value1 -s name2=value2.
       Note: the value may be an environment variable, e.g. -s sequence=$SEQUENCE

       Tracing options:
       -v: Prints the expressions's AST (abstract syntax tree), which gives
       full transparency on the precedence and associativity rules of
       Miller's grammar, to stdout.
       -a: Prints a low-level stack-allocation trace to stdout.
       -t: Prints a low-level parser trace to stderr.
       -T: Prints a every statement to stderr as it is executed.

       Other options:
       -x: Prints records for which {expression} evaluates to false.

       Please use a dollar sign for field names and double-quotes for string
       literals. If field names have special characters such as "." then you might
       use braces, e.g. '${field.name}'. Miller built-in variables are
       NF NR FNR FILENUM FILENAME M_PI M_E, and ENV["namegoeshere"] to access environment
       variables. The environment-variable name may be an expression, e.g. a field
       value.

       Use # to comment to end of line.

       Examples:
     mlr filter 'log10($count) > 4.0'
     mlr filter 'FNR == 2          (second record in each file)'
     mlr filter 'urand() < 0.001'  (subsampling)
     mlr filter '$color != "blue" && $value > 4.2'
     mlr filter '($x<.5 && $y<.5) || ($x>.5 && $y>.5)'
     mlr filter '($name =~ "^sys.*east$") || ($name =~ "^dev.[0-9]+"i)'
     mlr filter '$ab = $a+$b; $cd = $c+$d; $ab != $cd'
     mlr filter '
       NR == 1 ||
      #NR == 2 ||
       NR == 3
     '

       Please see http://johnkerl.org/miller/doc/reference.html for more information
       including function list. Or "mlr -f". Please also see "mlr grep" which is
       useful when you don't yet know which field name(s) you're looking for.
       Please see in particular:
     http://www.johnkerl.org/miller/doc/reference-verbs.html#filter

   format-values
       Usage: mlr format-values [options]
       Applies format strings to all field values, depending on autodetected type.
       * If a field value is detected to be integer, applies integer format.
       * Else, if a field value is detected to be float, applies float format.
       * Else, applies string format.

       Note: this is a low-keystroke way to apply formatting to many fields. To get
       finer control, please see the fmtnum function within the mlr put DSL.

       Note: this verb lets you apply arbitrary format strings, which can produce
       undefined behavior and/or program crashes.  See your system's "man printf".

       Options:
       -i {integer format} Defaults to "%lld".
                       Examples: "%06lld", "%08llx".
                       Note that Miller integers are long long so you must use
                       formats which apply to long long, e.g. with ll in them.
                       Undefined behavior results otherwise.
       -f {float format}   Defaults to "%lf".
                       Examples: "%8.3lf", "%.6le".
                       Note that Miller floats are double-precision so you must
                       use formats which apply to double, e.g. with l[efg] in them.
                       Undefined behavior results otherwise.
       -s {string format}  Defaults to "%s".
                       Examples: "_%s", "%08s".
                       Note that you must use formats which apply to string, e.g.
                       with s in them. Undefined behavior results otherwise.
       -n              Coerce field values autodetected as int to float, and then
                       apply the float format.

   fraction
       Usage: mlr fraction [options]
       For each record's value in specified fields, computes the ratio of that
       value to the sum of values in that field over all input records.
       E.g. with input records      x=1  x=2  x=3  and  x=4, emits output records
       x=1,x_fraction=0.1  x=2,x_fraction=0.2  x=3,x_fraction=0.3  and      x=4,x_fraction=0.4

       Note: this is internally a two-pass algorithm: on the first pass it retains
       input records and accumulates sums; on the second pass it computes quotients
       and emits output records. This means it produces no output until all input is read.

       Options:
       -f {a,b,c}    Field name(s) for fraction calculation
       -g {d,e,f}    Optional group-by-field name(s) for fraction counts
       -p        Produce percents [0..100], not fractions [0..1]. Output field names
                 end with "_percent" rather than "_fraction"
       -c        Produce cumulative distributions, i.e. running sums: each output
                 value folds in the sum of the previous for the specified group
                 E.g. with input records  x=1  x=2  x=3  and  x=4, emits output records
                 x=1,x_cumulative_fraction=0.1  x=2,x_cumulative_fraction=0.3
                 x=3,x_cumulative_fraction=0.6  and  x=4,x_cumulative_fraction=1.0

   grep
       Usage: mlr grep [options] {regular expression}
       Passes through records which match {regex}.
       Options:
       -i    Use case-insensitive search.
       -v    Invert: pass through records which do not match the regex.
       Note that "mlr filter" is more powerful, but requires you to know field names.
       By contrast, "mlr grep" allows you to regex-match the entire record. It does
       this by formatting each record in memory as DKVP, using command-line-specified
       ORS/OFS/OPS, and matching the resulting line against the regex specified
       here. In particular, the regex is not applied to the input stream: if you
       have CSV with header line "x,y,z" and data line "1,2,3" then the regex will
       be matched, not against either of these lines, but against the DKVP line
       "x=1,y=2,z=3".  Furthermore, not all the options to system grep are supported,
       and this command is intended to be merely a keystroke-saver. To get all the
       features of system grep, you can do
     "mlr --odkvp ... | grep ... | mlr --idkvp ..."

   group-by
       Usage: mlr group-by {comma-separated field names}
       Outputs records in batches having identical values at specified field names.

   group-like
       Usage: mlr group-like
       Outputs records in batches having identical field names.

   having-fields
       Usage: mlr having-fields [options]
       Conditionally passes through records depending on each record's field names.
       Options:
     --at-least      {comma-separated names}
     --which-are     {comma-separated names}
     --at-most       {comma-separated names}
     --all-matching  {regular expression}
     --any-matching  {regular expression}
     --none-matching {regular expression}
       Examples:
     mlr having-fields --which-are amount,status,owner
     mlr having-fields --any-matching 'sda[0-9]'
     mlr having-fields --any-matching '"sda[0-9]"'
     mlr having-fields --any-matching '"sda[0-9]"i' (this is case-insensitive)

   head
       Usage: mlr head [options]
       -n {count}    Head count to print; default 10
       -g {a,b,c}    Optional group-by-field names for head counts
       Passes through the first n records, optionally by category.
       Without -g, ceases consuming more input (i.e. is fast) when n
       records have been read.

   histogram
       Usage: mlr histogram [options]
       -f {a,b,c}    Value-field names for histogram counts
       --lo {lo}     Histogram low value
       --hi {hi}     Histogram high value
       --nbins {n}   Number of histogram bins
       --auto            Automatically computes limits, ignoring --lo and --hi.
                 Holds all values in memory before producing any output.
       -o {prefix}   Prefix for output field name. Default: no prefix.
       Just a histogram. Input values < lo or > hi are not counted.

   join
       Usage: mlr join [options]
       Joins records from specified left file name with records from all file names
       at the end of the Miller argument list.
       Functionality is essentially the same as the system "join" command, but for
       record streams.
       Options:
     -f {left file name}
     -j {a,b,c}   Comma-separated join-field names for output
     -l {a,b,c}   Comma-separated join-field names for left input file;
                  defaults to -j values if omitted.
     -r {a,b,c}   Comma-separated join-field names for right input file(s);
                  defaults to -j values if omitted.
     --lp {text}  Additional prefix for non-join output field names from
                  the left file
     --rp {text}  Additional prefix for non-join output field names from
                  the right file(s)
     --np         Do not emit paired records
     --ul         Emit unpaired records from the left file
     --ur         Emit unpaired records from the right file(s)
     -s|--sorted-input  Require sorted input: records must be sorted
                  lexically by their join-field names, else not all records will
                  be paired. The only likely use case for this is with a left
                  file which is too big to fit into system memory otherwise.
     -u           Enable unsorted input. (This is the default even without -u.)
                  In this case, the entire left file will be loaded into memory.
     --prepipe {command} As in main input options; see mlr --help for details.
                  If you wish to use a prepipe command for the main input as well
                  as here, it must be specified there as well as here.
       File-format options default to those for the right file names on the Miller
       argument list, but may be overridden for the left file as follows. Please see
       the main "mlr --help" for more information on syntax for these arguments.
     -i {one of csv,dkvp,nidx,pprint,xtab}
     --irs {record-separator character}
     --ifs {field-separator character}
     --ips {pair-separator character}
     --repifs
     --repips
       Please use "mlr --usage-separator-options" for information on specifying separators.
       Please see http://johnkerl.org/miller/doc/reference-verbs.html#join for more information
       including examples.

   label
       Usage: mlr label {new1,new2,new3,...}
       Given n comma-separated names, renames the first n fields of each record to
       have the respective name. (Fields past the nth are left with their original
       names.) Particularly useful with --inidx or --implicit-csv-header, to give
       useful names to otherwise integer-indexed fields.
       Examples:
     "echo 'a b c d' | mlr --inidx --odkvp cat"       gives "1=a,2=b,3=c,4=d"
     "echo 'a b c d' | mlr --inidx --odkvp label s,t" gives "s=a,t=b,3=c,4=d"

   least-frequent
       Usage: mlr least-frequent [options]
       Shows the least frequently occurring distinct values for specified field names.
       The first entry is the statistical anti-mode; the remaining are runners-up.
       Options:
       -f {one or more comma-separated field names}. Required flag.
       -n {count}. Optional flag defaulting to 10.
       -b      Suppress counts; show only field values.
       -o {name}   Field name for output count. Default "count".
       See also "mlr most-frequent".

   merge-fields
       Usage: mlr merge-fields [options]
       Computes univariate statistics for each input record, accumulated across
       specified fields.
       Options:
       -a {sum,count,...}  Names of accumulators. One or more of:
     count     Count instances of fields
     mode      Find most-frequently-occurring values for fields; first-found wins tie
     antimode  Find least-frequently-occurring values for fields; first-found wins tie
     sum       Compute sums of specified fields
     mean      Compute averages (sample means) of specified fields
     stddev    Compute sample standard deviation of specified fields
     var       Compute sample variance of specified fields
     meaneb    Estimate error bars for averages (assuming no sample autocorrelation)
     skewness  Compute sample skewness of specified fields
     kurtosis  Compute sample kurtosis of specified fields
     min       Compute minimum values of specified fields
     max       Compute maximum values of specified fields
       -f {a,b,c}  Value-field names on which to compute statistics. Requires -o.
       -r {a,b,c}  Regular expressions for value-field names on which to compute
               statistics. Requires -o.
       -c {a,b,c}  Substrings for collapse mode. All fields which have the same names
               after removing substrings will be accumulated together. Please see
               examples below.
       -i      Use interpolated percentiles, like R's type=7; default like type=1.
               Not sensical for string-valued fields.
       -o {name}   Output field basename for -f/-r.
       -k      Keep the input fields which contributed to the output statistics;
               the default is to omit them.
       -F      Computes integerable things (e.g. count) in floating point.

       String-valued data make sense unless arithmetic on them is required,
       e.g. for sum, mean, interpolated percentiles, etc. In case of mixed data,
       numbers are less than strings.

       Example input data: "a_in_x=1,a_out_x=2,b_in_y=4,b_out_x=8".
       Example: mlr merge-fields -a sum,count -f a_in_x,a_out_x -o foo
     produces "b_in_y=4,b_out_x=8,foo_sum=3,foo_count=2" since "a_in_x,a_out_x" are
     summed over.
       Example: mlr merge-fields -a sum,count -r in_,out_ -o bar
     produces "bar_sum=15,bar_count=4" since all four fields are summed over.
       Example: mlr merge-fields -a sum,count -c in_,out_
     produces "a_x_sum=3,a_x_count=2,b_y_sum=4,b_y_count=1,b_x_sum=8,b_x_count=1"
     since "a_in_x" and "a_out_x" both collapse to "a_x", "b_in_y" collapses to
     "b_y", and "b_out_x" collapses to "b_x".

   most-frequent
       Usage: mlr most-frequent [options]
       Shows the most frequently occurring distinct values for specified field names.
       The first entry is the statistical mode; the remaining are runners-up.
       Options:
       -f {one or more comma-separated field names}. Required flag.
       -n {count}. Optional flag defaulting to 10.
       -b      Suppress counts; show only field values.
       -o {name}   Field name for output count. Default "count".
       See also "mlr least-frequent".

   nest
       Usage: mlr nest [options]
       Explodes specified field values into separate fields/records, or reverses this.
       Options:
     --explode,--implode   One is required.
     --values,--pairs      One is required.
     --across-records,--across-fields One is required.
     -f {field name}       Required.
     --nested-fs {string}  Defaults to ";". Field separator for nested values.
     --nested-ps {string}  Defaults to ":". Pair separator for nested key-value pairs.
     --evar {string}       Shorthand for --explode --values ---across-records --nested-fs {string}
     --ivar {string}       Shorthand for --implode --values ---across-records --nested-fs {string}
       Please use "mlr --usage-separator-options" for information on specifying separators.

       Examples:

     mlr nest --explode --values --across-records -f x
     with input record "x=a;b;c,y=d" produces output records
       "x=a,y=d"
       "x=b,y=d"
       "x=c,y=d"
     Use --implode to do the reverse.

     mlr nest --explode --values --across-fields -f x
     with input record "x=a;b;c,y=d" produces output records
       "x_1=a,x_2=b,x_3=c,y=d"
     Use --implode to do the reverse.

     mlr nest --explode --pairs --across-records -f x
     with input record "x=a:1;b:2;c:3,y=d" produces output records
       "a=1,y=d"
       "b=2,y=d"
       "c=3,y=d"

     mlr nest --explode --pairs --across-fields -f x
     with input record "x=a:1;b:2;c:3,y=d" produces output records
       "a=1,b=2,c=3,y=d"

       Notes:
       * With --pairs, --implode doesn't make sense since the original field name has
     been lost.
       * The combination "--implode --values --across-records" is non-streaming:
     no output records are produced until all input records have been read. In
     particular, this means it won't work in tail -f contexts. But all other flag
     combinations result in streaming (tail -f friendly) data processing.
       * It's up to you to ensure that the nested-fs is distinct from your data's IFS:
     e.g. by default the former is semicolon and the latter is comma.
       See also mlr reshape.

   nothing
       Usage: mlr nothing
       Drops all input records. Useful for testing, or after tee/print/etc. have
       produced other output.

   put
       Usage: mlr put [options] {expression}
       Adds/updates specified field(s). Expressions are semicolon-separated and must
       either be assignments, or evaluate to boolean.  Booleans with following
       statements in curly braces control whether those statements are executed;
       booleans without following curly braces do nothing except side effects (e.g.
       regex-captures into \1, \2, etc.).

       Conversion options:
       -S: Keeps field values as strings with no type inference to int or float.
       -F: Keeps field values as strings or floats with no inference to int.
       All field values are type-inferred to int/float/string unless this behavior is
       suppressed with -S or -F.

       Output/formatting options:
       --oflatsep {string}: Separator to use when flattening multi-level @-variables
       to output records for emit. Default ":".
       --jknquoteint: For dump output (JSON-formatted), do not quote map keys if non-string.
       --jvquoteall: For dump output (JSON-formatted), quote map values even if non-string.
       Any of the output-format command-line flags (see mlr -h). Example: using
     mlr --icsv --opprint ... then put --ojson 'tee > "mytap-".$a.".dat", $*' then ...
       the input is CSV, the output is pretty-print tabular, but the tee-file output
       is written in JSON format.
       --no-fflush: for emit, tee, print, and dump, don't call fflush() after every
       record.

       Expression-specification options:
       -f {filename}: the DSL expression is taken from the specified file rather
       than from the command line. Outer single quotes wrapping the expression
       should not be placed in the file. If -f is specified more than once,
       all input files specified using -f are concatenated to produce the expression.
       (For example, you can define functions in one file and call them from another.)
       -e {expression}: You can use this after -f to add an expression. Example use
       case: define functions/subroutines in a file you specify with -f, then call
       them with an expression you specify with -e.
       (If you mix -e and -f then the expressions are evaluated in the order encountered.
       Since the expression pieces are simply concatenated, please be sure to use intervening
       semicolons to separate expressions.)

       -s name=value: Predefines out-of-stream variable @name to have value "value".
       Thus mlr put put -s foo=97 '$column += @foo' is like
       mlr put put 'begin {@foo = 97} $column += @foo'.
       The value part is subject to type-inferencing as specified by -S/-F.
       May be specified more than once, e.g. -s name1=value1 -s name2=value2.
       Note: the value may be an environment variable, e.g. -s sequence=$SEQUENCE

       Tracing options:
       -v: Prints the expressions's AST (abstract syntax tree), which gives
       full transparency on the precedence and associativity rules of
       Miller's grammar, to stdout.
       -a: Prints a low-level stack-allocation trace to stdout.
       -t: Prints a low-level parser trace to stderr.
       -T: Prints a every statement to stderr as it is executed.

       Other options:
       -q: Does not include the modified record in the output stream. Useful for when
       all desired output is in begin and/or end blocks.

       Please use a dollar sign for field names and double-quotes for string
       literals. If field names have special characters such as "." then you might
       use braces, e.g. '${field.name}'. Miller built-in variables are
       NF NR FNR FILENUM FILENAME M_PI M_E, and ENV["namegoeshere"] to access environment
       variables. The environment-variable name may be an expression, e.g. a field
       value.

       Use # to comment to end of line.

       Examples:
     mlr put '$y = log10($x); $z = sqrt($y)'
     mlr put '$x>0.0 { $y=log10($x); $z=sqrt($y) }' # does {...} only if $x > 0.0
     mlr put '$x>0.0;  $y=log10($x); $z=sqrt($y)'   # does all three statements
     mlr put '$a =~ "([a-z]+)_([0-9]+);  $b = "left_\1"; $c = "right_\2"'
     mlr put '$a =~ "([a-z]+)_([0-9]+) { $b = "left_\1"; $c = "right_\2" }'
     mlr put '$filename = FILENAME'
     mlr put '$colored_shape = $color . "_" . $shape'
     mlr put '$y = cos($theta); $z = atan2($y, $x)'
     mlr put '$name = sub($name, "http.*com"i, "")'
     mlr put -q '@sum += $x; end {emit @sum}'
     mlr put -q '@sum[$a] += $x; end {emit @sum, "a"}'
     mlr put -q '@sum[$a][$b] += $x; end {emit @sum, "a", "b"}'
     mlr put -q '@min=min(@min,$x);@max=max(@max,$x); end{emitf @min, @max}'
     mlr put -q 'is_null(@xmax) || $x > @xmax {@xmax=$x; @recmax=$*}; end {emit @recmax}'
     mlr put '
       $x = 1;
      #$y = 2;
       $z = 3
     '

       Please see also 'mlr -k' for examples using redirected output.

       Please see http://johnkerl.org/miller/doc/reference.html for more information
       including function list. Or "mlr -f".
       Please see in particular:
     http://www.johnkerl.org/miller/doc/reference-verbs.html#put

   regularize
       Usage: mlr regularize
       For records seen earlier in the data stream with same field names in
       a different order, outputs them with field names in the previously
       encountered order.
       Example: input records a=1,c=2,b=3, then e=4,d=5, then c=7,a=6,b=8
       output as          a=1,c=2,b=3, then e=4,d=5, then a=6,c=7,b=8

   remove-empty-columns
       Usage: mlr remove-empty-columns
       Omits fields which are empty on every input row. Non-streaming.

   rename
       Usage: mlr rename [options] {old1,new1,old2,new2,...}
       Renames specified fields.
       Options:
       -r     Treat old field  names as regular expressions. "ab", "a.*b"
              will match any field name containing the substring "ab" or
              matching "a.*b", respectively; anchors of the form "^ab$",
              "^a.*b$" may be used. New field names may be plain strings,
              or may contain capture groups of the form "\1" through
              "\9". Wrapping the regex in double quotes is optional, but
              is required if you wish to follow it with 'i' to indicate
              case-insensitivity.
       -g     Do global replacement within each field name rather than
              first-match replacement.
       Examples:
       mlr rename old_name,new_name'
       mlr rename old_name_1,new_name_1,old_name_2,new_name_2'
       mlr rename -r 'Date_[0-9]+,Date,'  Rename all such fields to be "Date"
       mlr rename -r '"Date_[0-9]+",Date' Same
       mlr rename -r 'Date_([0-9]+).*,\1' Rename all such fields to be of the form 20151015
       mlr rename -r '"name"i,Name'   Rename "name", "Name", "NAME", etc. to "Name"

   reorder
       Usage: mlr reorder [options]
       -f {a,b,c}   Field names to reorder.
       -e       Put specified field names at record end: default is to put
                them at record start.
       Examples:
       mlr reorder    -f a,b sends input record "d=4,b=2,a=1,c=3" to "a=1,b=2,d=4,c=3".
       mlr reorder -e -f a,b sends input record "d=4,b=2,a=1,c=3" to "d=4,c=3,a=1,b=2".

   repeat
       Usage: mlr repeat [options]
       Copies input records to output records multiple times.
       Options must be exactly one of the following:
     -n {repeat count}  Repeat each input record this many times.
     -f {field name}    Same, but take the repeat count from the specified
                        field name of each input record.
       Example:
     echo x=0 | mlr repeat -n 4 then put '$x=urand()'
       produces:
    x=0.488189
    x=0.484973
    x=0.704983
    x=0.147311
       Example:
     echo a=1,b=2,c=3 | mlr repeat -f b
       produces:
     a=1,b=2,c=3
     a=1,b=2,c=3
       Example:
     echo a=1,b=2,c=3 | mlr repeat -f c
       produces:
     a=1,b=2,c=3
     a=1,b=2,c=3
     a=1,b=2,c=3

   reshape
       Usage: mlr reshape [options]
       Wide-to-long options:
     -i {input field names}   -o {key-field name,value-field name}
     -r {input field regexes} -o {key-field name,value-field name}
     These pivot/reshape the input data such that the input fields are removed
     and separate records are emitted for each key/value pair.
     Note: this works with tail -f and produces output records for each input
     record seen.
       Long-to-wide options:
     -s {key-field name,value-field name}
     These pivot/reshape the input data to undo the wide-to-long operation.
     Note: this does not work with tail -f; it produces output records only after
     all input records have been read.

       Examples:

     Input file "wide.txt":
       time       X           Y
       2009-01-01 0.65473572  2.4520609
       2009-01-02 -0.89248112 0.2154713
       2009-01-03 0.98012375  1.3179287

     mlr --pprint reshape -i X,Y -o item,value wide.txt
       time       item value
       2009-01-01 X    0.65473572
       2009-01-01 Y    2.4520609
       2009-01-02 X    -0.89248112
       2009-01-02 Y    0.2154713
       2009-01-03 X    0.98012375
       2009-01-03 Y    1.3179287

     mlr --pprint reshape -r '[A-Z]' -o item,value wide.txt
       time       item value
       2009-01-01 X    0.65473572
       2009-01-01 Y    2.4520609
       2009-01-02 X    -0.89248112
       2009-01-02 Y    0.2154713
       2009-01-03 X    0.98012375
       2009-01-03 Y    1.3179287

     Input file "long.txt":
       time       item value
       2009-01-01 X    0.65473572
       2009-01-01 Y    2.4520609
       2009-01-02 X    -0.89248112
       2009-01-02 Y    0.2154713
       2009-01-03 X    0.98012375
       2009-01-03 Y    1.3179287

     mlr --pprint reshape -s item,value long.txt
       time       X           Y
       2009-01-01 0.65473572  2.4520609
       2009-01-02 -0.89248112 0.2154713
       2009-01-03 0.98012375  1.3179287
       See also mlr nest.

   sample
       Usage: mlr sample [options]
       Reservoir sampling (subsampling without replacement), optionally by category.
       -k {count}    Required: number of records to output, total, or by group if using -g.
       -g {a,b,c}    Optional: group-by-field names for samples.
       See also mlr bootstrap and mlr shuffle.

   sec2gmt
       Usage: mlr sec2gmt [options] {comma-separated list of field names}
       Replaces a numeric field representing seconds since the epoch with the
       corresponding GMT timestamp; leaves non-numbers as-is. This is nothing
       more than a keystroke-saver for the sec2gmt function:
     mlr sec2gmt time1,time2
       is the same as
     mlr put '$time1=sec2gmt($time1);$time2=sec2gmt($time2)'
       Options:
       -1 through -9: format the seconds using 1..9 decimal places, respectively.

   sec2gmtdate
       Usage: mlr sec2gmtdate {comma-separated list of field names}
       Replaces a numeric field representing seconds since the epoch with the
       corresponding GMT year-month-day timestamp; leaves non-numbers as-is.
       This is nothing more than a keystroke-saver for the sec2gmtdate function:
     mlr sec2gmtdate time1,time2
       is the same as
     mlr put '$time1=sec2gmtdate($time1);$time2=sec2gmtdate($time2)'

   seqgen
       Usage: mlr seqgen [options]
       Produces a sequence of counters.  Discards the input record stream. Produces
       output as specified by the following options:
       -f {name} Field name for counters; default "i".
       --start {number} Inclusive start value; default "1".
       --stop  {number} Inclusive stop value; default "100".
       --step  {number} Step value; default "1".
       Start, stop, and/or step may be floating-point. Output is integer if start,
       stop, and step are all integers. Step may be negative. It may not be zero
       unless start == stop.

   shuffle
       Usage: mlr shuffle {no options}
       Outputs records randomly permuted. No output records are produced until
       all input records are read.
       See also mlr bootstrap and mlr sample.

   skip-trivial-records
       Usage: mlr skip-trivial-records [options]
       Passes through all records except:
       * those with zero fields;
       * those for which all fields have empty value.

   sort
       Usage: mlr sort {flags}
       Flags:
     -f  {comma-separated field names}  Lexical ascending
     -n  {comma-separated field names}  Numerical ascending; nulls sort last
     -nf {comma-separated field names}  Same as -n
     -r  {comma-separated field names}  Lexical descending
     -nr {comma-separated field names}  Numerical descending; nulls sort first
       Sorts records primarily by the first specified field, secondarily by the second
       field, and so on.  (Any records not having all specified sort keys will appear
       at the end of the output, in the order they were encountered, regardless of the
       specified sort order.) The sort is stable: records that compare equal will sort
       in the order they were encountered in the input record stream.

       Example:
     mlr sort -f a,b -nr x,y,z
       which is the same as:
     mlr sort -f a -f b -nr x -nr y -nr z

   stats1
       Usage: mlr stats1 [options]
       Computes univariate statistics for one or more given fields, accumulated across
       the input record stream.
       Options:
       -a {sum,count,...}  Names of accumulators: p10 p25.2 p50 p98 p100 etc. and/or
                       one or more of:
      count     Count instances of fields
      mode      Find most-frequently-occurring values for fields; first-found wins tie
      antimode  Find least-frequently-occurring values for fields; first-found wins tie
      sum       Compute sums of specified fields
      mean      Compute averages (sample means) of specified fields
      stddev    Compute sample standard deviation of specified fields
      var       Compute sample variance of specified fields
      meaneb    Estimate error bars for averages (assuming no sample autocorrelation)
      skewness  Compute sample skewness of specified fields
      kurtosis  Compute sample kurtosis of specified fields
      min       Compute minimum values of specified fields
      max       Compute maximum values of specified fields
       -f {a,b,c}   Value-field names on which to compute statistics
       --fr {regex} Regex for value-field names on which to compute statistics
                (compute statistics on values in all field names matching regex)
       --fx {regex} Inverted regex for value-field names on which to compute statistics
                (compute statistics on values in all field names not matching regex)
       -g {d,e,f}   Optional group-by-field names
       --gr {regex} Regex for optional group-by-field names
                (group by values in field names matching regex)
       --gx {regex} Inverted regex for optional group-by-field names
                (group by values in field names not matching regex)
       --grfx {regex} Shorthand for --gr {regex} --fx {that same regex}
       -i       Use interpolated percentiles, like R's type=7; default like type=1.
                Not sensical for string-valued fields.
       -s       Print iterative stats. Useful in tail -f contexts (in which
                case please avoid pprint-format output since end of input
                stream will never be seen).
       -F       Computes integerable things (e.g. count) in floating point.
       Example: mlr stats1 -a min,p10,p50,p90,max -f value -g size,shape
       Example: mlr stats1 -a count,mode -f size
       Example: mlr stats1 -a count,mode -f size -g shape
       Example: mlr stats1 -a count,mode --fr '^[a-h].*$' -gr '^k.*$'
            This computes count and mode statistics on all field names beginning
            with a through h, grouped by all field names starting with k.
       Notes:
       * p50 and median are synonymous.
       * min and max output the same results as p0 and p100, respectively, but use
     less memory.
       * String-valued data make sense unless arithmetic on them is required,
     e.g. for sum, mean, interpolated percentiles, etc. In case of mixed data,
     numbers are less than strings.
       * count and mode allow text input; the rest require numeric input.
     In particular, 1 and 1.0 are distinct text for count and mode.
       * When there are mode ties, the first-encountered datum wins.

   stats2
       Usage: mlr stats2 [options]
       Computes bivariate statistics for one or more given field-name pairs,
       accumulated across the input record stream.
       -a {linreg-ols,corr,...}  Names of accumulators: one or more of:
     linreg-pca   Linear regression using principal component analysis
     linreg-ols   Linear regression using ordinary least squares
     r2           Quality metric for linreg-ols (linreg-pca emits its own)
     logireg      Logistic regression
     corr         Sample correlation
     cov          Sample covariance
     covx         Sample-covariance matrix
       -f {a,b,c,d}   Value-field name-pairs on which to compute statistics.
                  There must be an even number of names.
       -g {e,f,g}     Optional group-by-field names.
       -v         Print additional output for linreg-pca.
       -s         Print iterative stats. Useful in tail -f contexts (in which
                  case please avoid pprint-format output since end of input
                  stream will never be seen).
       --fit              Rather than printing regression parameters, applies them to
                  the input data to compute new fit fields. All input records are
                  held in memory until end of input stream. Has effect only for
                  linreg-ols, linreg-pca, and logireg.
       Only one of -s or --fit may be used.
       Example: mlr stats2 -a linreg-pca -f x,y
       Example: mlr stats2 -a linreg-ols,r2 -f x,y -g size,shape
       Example: mlr stats2 -a corr -f x,y

   step
       Usage: mlr step [options]
       Computes values dependent on the previous record, optionally grouped
       by category.

       Options:
       -a {delta,rsum,...}   Names of steppers: comma-separated, one or more of:
     delta    Compute differences in field(s) between successive records
     shift    Include value(s) in field(s) from previous record, if any
     from-first Compute differences in field(s) from first record
     ratio    Compute ratios in field(s) between successive records
     rsum     Compute running sums of field(s) between successive records
     counter  Count instances of field(s) between successive records
     ewma     Exponentially weighted moving average over successive records
       -f {a,b,c} Value-field names on which to compute statistics
       -g {d,e,f} Optional group-by-field names
       -F     Computes integerable things (e.g. counter) in floating point.
       -d {x,y,z} Weights for ewma. 1 means current sample gets all weight (no
              smoothing), near under under 1 is light smoothing, near over 0 is
              heavy smoothing. Multiple weights may be specified, e.g.
              "mlr step -a ewma -f sys_load -d 0.01,0.1,0.9". Default if omitted
              is "-d 0.5".
       -o {a,b,c} Custom suffixes for EWMA output fields. If omitted, these default to
              the -d values. If supplied, the number of -o values must be the same
              as the number of -d values.

       Examples:
     mlr step -a rsum -f request_size
     mlr step -a delta -f request_size -g hostname
     mlr step -a ewma -d 0.1,0.9 -f x,y
     mlr step -a ewma -d 0.1,0.9 -o smooth,rough -f x,y
     mlr step -a ewma -d 0.1,0.9 -o smooth,rough -f x,y -g group_name

       Please see http://johnkerl.org/miller/doc/reference-verbs.html#filter or
       https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average
       for more information on EWMA.

   tac
       Usage: mlr tac
       Prints records in reverse order from the order in which they were encountered.

   tail
       Usage: mlr tail [options]
       -n {count}    Tail count to print; default 10
       -g {a,b,c}    Optional group-by-field names for tail counts
       Passes through the last n records, optionally by category.

   tee
       Usage: mlr tee [options] {filename}
       Passes through input records (like mlr cat) but also writes to specified output
       file, using output-format flags from the command line (e.g. --ocsv). See also
       the "tee" keyword within mlr put, which allows data-dependent filenames.
       Options:
       -a:      append to existing file, if any, rather than overwriting.
       --no-fflush: don't call fflush() after every record.
       Any of the output-format command-line flags (see mlr -h). Example: using
     mlr --icsv --opprint put '...' then tee --ojson ./mytap.dat then stats1 ...
       the input is CSV, the output is pretty-print tabular, but the tee-file output
       is written in JSON format.

   top
       Usage: mlr top [options]
       -f {a,b,c}    Value-field names for top counts.
       -g {d,e,f}    Optional group-by-field names for top counts.
       -n {count}    How many records to print per category; default 1.
       -a        Print all fields for top-value records; default is
                 to print only value and group-by fields. Requires a single
                 value-field name only.
       --min             Print top smallest values; default is top largest values.
       -F        Keep top values as floats even if they look like integers.
       -o {name}     Field name for output indices. Default "top_idx".
       Prints the n records with smallest/largest values at specified fields,
       optionally by category.

   uniq
       Usage: mlr uniq [options]
       Prints distinct values for specified field names. With -c, same as
       count-distinct. For uniq, -f is a synonym for -g.

       Options:
       -g {d,e,f}    Group-by-field names for uniq counts.
       -c        Show repeat counts in addition to unique values.
       -n        Show only the number of distinct values.
       -o {name}     Field name for output count. Default "count".
       -a        Output each unique record only once. Incompatible with -g.
                 With -c, produces unique records, with repeat counts for each.
                 With -n, produces only one record which is the unique-record count.
                 With neither -c nor -n, produces unique records.

   unsparsify
       Usage: mlr unsparsify [options]
       Prints records with the union of field names over all input records.
       For field names absent in a given record but present in others, fills in
       a value. This verb retains all input before producing any output.

       Options:
       --fill-with {filler string}  What to fill absent fields with. Defaults to
                                the empty string.

       Example: if the input is two records, one being 'a=1,b=2' and the other
       being 'b=3,c=4', then the output is the two records 'a=1,b=2,c=' and
       'a=,b=3,c=4'.

FUNCTIONS FOR FILTER/PUT
   +
       (class=arithmetic #args=2): Addition.

       + (class=arithmetic #args=1): Unary plus.

   -
       (class=arithmetic #args=2): Subtraction.

       - (class=arithmetic #args=1): Unary minus.

   *
       (class=arithmetic #args=2): Multiplication.

   /
       (class=arithmetic #args=2): Division.

   //
       (class=arithmetic #args=2): Integer division: rounds to negative (pythonic).

   .+
       (class=arithmetic #args=2): Addition, with integer-to-integer overflow

       .+ (class=arithmetic #args=1): Unary plus, with integer-to-integer overflow.

   .-
       (class=arithmetic #args=2): Subtraction, with integer-to-integer overflow.

       .- (class=arithmetic #args=1): Unary minus, with integer-to-integer overflow.

   .*
       (class=arithmetic #args=2): Multiplication, with integer-to-integer overflow.

   ./
       (class=arithmetic #args=2): Division, with integer-to-integer overflow.

   .//
       (class=arithmetic #args=2): Integer division: rounds to negative (pythonic), with integer-to-integer overflow.

   %
       (class=arithmetic #args=2): Remainder; never negative-valued (pythonic).

   **
       (class=arithmetic #args=2): Exponentiation; same as pow, but as an infix
       operator.

   |
       (class=arithmetic #args=2): Bitwise OR.

   ^
       (class=arithmetic #args=2): Bitwise XOR.

   &
       (class=arithmetic #args=2): Bitwise AND.

   ~
       (class=arithmetic #args=1): Bitwise NOT. Beware '$y=~$x' since =~ is the
       regex-match operator: try '$y = ~$x'.

   <<
       (class=arithmetic #args=2): Bitwise left-shift.

   >>
       (class=arithmetic #args=2): Bitwise right-shift.

   bitcount
       (class=arithmetic #args=1): Count of 1-bits

   ==
       (class=boolean #args=2): String/numeric equality. Mixing number and string
       results in string compare.

   !=
       (class=boolean #args=2): String/numeric inequality. Mixing number and string
       results in string compare.

   =~
       (class=boolean #args=2): String (left-hand side) matches regex (right-hand
       side), e.g. '$name =~ "^a.*b$"'.

   !=~
       (class=boolean #args=2): String (left-hand side) does not match regex
       (right-hand side), e.g. '$name !=~ "^a.*b$"'.

   >
       (class=boolean #args=2): String/numeric greater-than. Mixing number and string
       results in string compare.

   >=
       (class=boolean #args=2): String/numeric greater-than-or-equals. Mixing number
       and string results in string compare.

   <
       (class=boolean #args=2): String/numeric less-than. Mixing number and string
       results in string compare.

   <=
       (class=boolean #args=2): String/numeric less-than-or-equals. Mixing number
       and string results in string compare.

   &&
       (class=boolean #args=2): Logical AND.

   ||
       (class=boolean #args=2): Logical OR.

   ^^
       (class=boolean #args=2): Logical XOR.

   !
       (class=boolean #args=1): Logical negation.

   ? :
       (class=boolean #args=3): Ternary operator.

   .
       (class=string #args=2): String concatenation.

   gsub
       (class=string #args=3): Example: '$name=gsub($name, "old", "new")'
       (replace all).

   regextract
       (class=string #args=2): Example: '$name=regextract($name, "[A-Z]{3}[0-9]{2}")'
       .

   regextract_or_else
       (class=string #args=3): Example: '$name=regextract_or_else($name, "[A-Z]{3}[0-9]{2}", "default")'
       .

   strlen
       (class=string #args=1): String length.

   sub
       (class=string #args=3): Example: '$name=sub($name, "old", "new")'
       (replace once).

   ssub
       (class=string #args=3): Like sub but does no regexing. No characters are special.

   substr
       (class=string #args=3): substr(s,m,n) gives substring of s from 0-up position m to n
       inclusive. Negative indices -len .. -1 alias to 0 .. len-1.

   tolower
       (class=string #args=1): Convert string to lowercase.

   toupper
       (class=string #args=1): Convert string to uppercase.

   capitalize
       (class=string #args=1): Convert string's first character to uppercase.

   lstrip
       (class=string #args=1): Strip leading whitespace from string.

   rstrip
       (class=string #args=1): Strip trailing whitespace from string.

   strip
       (class=string #args=1): Strip leading and trailing whitespace from string.

   collapse_whitespace
       (class=string #args=1): Strip repeated whitespace from string.

   clean_whitespace
       (class=string #args=1): Same as collapse_whitespace and strip.

   system
       (class=string #args=1): Run command string, yielding its stdout minus final carriage return.

   abs
       (class=math #args=1): Absolute value.

   acos
       (class=math #args=1): Inverse trigonometric cosine.

   acosh
       (class=math #args=1): Inverse hyperbolic cosine.

   asin
       (class=math #args=1): Inverse trigonometric sine.

   asinh
       (class=math #args=1): Inverse hyperbolic sine.

   atan
       (class=math #args=1): One-argument arctangent.

   atan2
       (class=math #args=2): Two-argument arctangent.

   atanh
       (class=math #args=1): Inverse hyperbolic tangent.

   cbrt
       (class=math #args=1): Cube root.

   ceil
       (class=math #args=1): Ceiling: nearest integer at or above.

   cos
       (class=math #args=1): Trigonometric cosine.

   cosh
       (class=math #args=1): Hyperbolic cosine.

   erf
       (class=math #args=1): Error function.

   erfc
       (class=math #args=1): Complementary error function.

   exp
       (class=math #args=1): Exponential function e**x.

   expm1
       (class=math #args=1): e**x - 1.

   floor
       (class=math #args=1): Floor: nearest integer at or below.

   invqnorm
       (class=math #args=1): Inverse of normal cumulative distribution
       function. Note that invqorm(urand()) is normally distributed.

   log
       (class=math #args=1): Natural (base-e) logarithm.

   log10
       (class=math #args=1): Base-10 logarithm.

   log1p
       (class=math #args=1): log(1-x).

   logifit
       (class=math #args=3): Given m and b from logistic regression, compute
       fit: $yhat=logifit($x,$m,$b).

   madd
       (class=math #args=3): a + b mod m (integers)

   max
       (class=math variadic): max of n numbers; null loses

   mexp
       (class=math #args=3): a ** b mod m (integers)

   min
       (class=math variadic): Min of n numbers; null loses

   mmul
       (class=math #args=3): a * b mod m (integers)

   msub
       (class=math #args=3): a - b mod m (integers)

   pow
       (class=math #args=2): Exponentiation; same as **.

   qnorm
       (class=math #args=1): Normal cumulative distribution function.

   round
       (class=math #args=1): Round to nearest integer.

   roundm
       (class=math #args=2): Round to nearest multiple of m: roundm($x,$m) is
       the same as round($x/$m)*$m

   sgn
       (class=math #args=1): +1 for positive input, 0 for zero input, -1 for
       negative input.

   sin
       (class=math #args=1): Trigonometric sine.

   sinh
       (class=math #args=1): Hyperbolic sine.

   sqrt
       (class=math #args=1): Square root.

   tan
       (class=math #args=1): Trigonometric tangent.

   tanh
       (class=math #args=1): Hyperbolic tangent.

   urand
       (class=math #args=0): Floating-point numbers uniformly distributed on the unit interval.
       Int-valued example: '$n=floor(20+urand()*11)'.

   urandrange
       (class=math #args=2): Floating-point numbers uniformly distributed on the interval [a, b).

   urand32
       (class=math #args=0): Integer uniformly distributed 0 and 2**32-1
       inclusive.

   urandint
       (class=math #args=2): Integer uniformly distributed between inclusive
       integer endpoints.

   dhms2fsec
       (class=time #args=1): Recovers floating-point seconds as in
       dhms2fsec("5d18h53m20.250000s") = 500000.250000

   dhms2sec
       (class=time #args=1): Recovers integer seconds as in
       dhms2sec("5d18h53m20s") = 500000

   fsec2dhms
       (class=time #args=1): Formats floating-point seconds as in
       fsec2dhms(500000.25) = "5d18h53m20.250000s"

   fsec2hms
       (class=time #args=1): Formats floating-point seconds as in
       fsec2hms(5000.25) = "01:23:20.250000"

   gmt2sec
       (class=time #args=1): Parses GMT timestamp as integer seconds since
       the epoch.

   localtime2sec
       (class=time #args=1): Parses local timestamp as integer seconds since
       the epoch. Consults $TZ environment variable.

   hms2fsec
       (class=time #args=1): Recovers floating-point seconds as in
       hms2fsec("01:23:20.250000") = 5000.250000

   hms2sec
       (class=time #args=1): Recovers integer seconds as in
       hms2sec("01:23:20") = 5000

   sec2dhms
       (class=time #args=1): Formats integer seconds as in sec2dhms(500000)
       = "5d18h53m20s"

   sec2gmt
       (class=time #args=1): Formats seconds since epoch (integer part)
       as GMT timestamp, e.g. sec2gmt(1440768801.7) = "2015-08-28T13:33:21Z".
       Leaves non-numbers as-is.

       sec2gmt (class=time #args=2): Formats seconds since epoch as GMT timestamp with n
       decimal places for seconds, e.g. sec2gmt(1440768801.7,1) = "2015-08-28T13:33:21.7Z".
       Leaves non-numbers as-is.

   sec2gmtdate
       (class=time #args=1): Formats seconds since epoch (integer part)
       as GMT timestamp with year-month-date, e.g. sec2gmtdate(1440768801.7) = "2015-08-28".
       Leaves non-numbers as-is.

   sec2localtime
       (class=time #args=1): Formats seconds since epoch (integer part)
       as local timestamp, e.g. sec2localtime(1440768801.7) = "2015-08-28T13:33:21Z".
       Consults $TZ environment variable. Leaves non-numbers as-is.

       sec2localtime (class=time #args=2): Formats seconds since epoch as local timestamp with n
       decimal places for seconds, e.g. sec2localtime(1440768801.7,1) = "2015-08-28T13:33:21.7Z".
       Consults $TZ environment variable. Leaves non-numbers as-is.

   sec2localdate
       (class=time #args=1): Formats seconds since epoch (integer part)
       as local timestamp with year-month-date, e.g. sec2localdate(1440768801.7) = "2015-08-28".
       Consults $TZ environment variable. Leaves non-numbers as-is.

   sec2hms
       (class=time #args=1): Formats integer seconds as in
       sec2hms(5000) = "01:23:20"

   strftime
       (class=time #args=2): Formats seconds since the epoch as timestamp, e.g.
       strftime(1440768801.7,"%Y-%m-%dT%H:%M:%SZ") = "2015-08-28T13:33:21Z", and
       strftime(1440768801.7,"%Y-%m-%dT%H:%M:%3SZ") = "2015-08-28T13:33:21.700Z".
       Format strings are as in the C library (please see "man strftime" on your system),
       with the Miller-specific addition of "%1S" through "%9S" which format the seconds
       with 1 through 9 decimal places, respectively. ("%S" uses no decimal places.)
       See also strftime_local.

   strftime_local
       (class=time #args=2): Like strftime but consults the $TZ environment variable to get local time zone.

   strptime
       (class=time #args=2): Parses timestamp as floating-point seconds since the epoch,
       e.g. strptime("2015-08-28T13:33:21Z","%Y-%m-%dT%H:%M:%SZ") = 1440768801.000000,
       and  strptime("2015-08-28T13:33:21.345Z","%Y-%m-%dT%H:%M:%SZ") = 1440768801.345000.
       See also strptime_local.

   strptime_local
       (class=time #args=2): Like strptime, but consults $TZ environment variable to find and use local timezone.

   systime
       (class=time #args=0): Floating-point seconds since the epoch,
       e.g. 1440768801.748936.

   is_absent
       (class=typing #args=1): False if field is present in input, true otherwise

   is_bool
       (class=typing #args=1): True if field is present with boolean value. Synonymous with is_boolean.

   is_boolean
       (class=typing #args=1): True if field is present with boolean value. Synonymous with is_bool.

   is_empty
       (class=typing #args=1): True if field is present in input with empty string value, false otherwise.

   is_empty_map
       (class=typing #args=1): True if argument is a map which is empty.

   is_float
       (class=typing #args=1): True if field is present with value inferred to be float

   is_int
       (class=typing #args=1): True if field is present with value inferred to be int

   is_map
       (class=typing #args=1): True if argument is a map.

   is_nonempty_map
       (class=typing #args=1): True if argument is a map which is non-empty.

   is_not_empty
       (class=typing #args=1): False if field is present in input with empty value, true otherwise

   is_not_map
       (class=typing #args=1): True if argument is not a map.

   is_not_null
       (class=typing #args=1): False if argument is null (empty or absent), true otherwise.

   is_null
       (class=typing #args=1): True if argument is null (empty or absent), false otherwise.

   is_numeric
       (class=typing #args=1): True if field is present with value inferred to be int or float

   is_present
       (class=typing #args=1): True if field is present in input, false otherwise.

   is_string
       (class=typing #args=1): True if field is present with string (including empty-string) value

   asserting_absent
       (class=typing #args=1): Returns argument if it is absent in the input data, else
       throws an error.

   asserting_bool
       (class=typing #args=1): Returns argument if it is present with boolean value, else
       throws an error.

   asserting_boolean
       (class=typing #args=1): Returns argument if it is present with boolean value, else
       throws an error.

   asserting_empty
       (class=typing #args=1): Returns argument if it is present in input with empty value,
       else throws an error.

   asserting_empty_map
       (class=typing #args=1): Returns argument if it is a map with empty value, else
       throws an error.

   asserting_float
       (class=typing #args=1): Returns argument if it is present with float value, else
       throws an error.

   asserting_int
       (class=typing #args=1): Returns argument if it is present with int value, else
       throws an error.

   asserting_map
       (class=typing #args=1): Returns argument if it is a map, else throws an error.

   asserting_nonempty_map
       (class=typing #args=1): Returns argument if it is a non-empty map, else throws
       an error.

   asserting_not_empty
       (class=typing #args=1): Returns argument if it is present in input with non-empty
       value, else throws an error.

   asserting_not_map
       (class=typing #args=1): Returns argument if it is not a map, else throws an error.

   asserting_not_null
       (class=typing #args=1): Returns argument if it is non-null (non-empty and non-absent),
       else throws an error.

   asserting_null
       (class=typing #args=1): Returns argument if it is null (empty or absent), else throws
       an error.

   asserting_numeric
       (class=typing #args=1): Returns argument if it is present with int or float value,
       else throws an error.

   asserting_present
       (class=typing #args=1): Returns argument if it is present in input, else throws
       an error.

   asserting_string
       (class=typing #args=1): Returns argument if it is present with string (including
       empty-string) value, else throws an error.

   boolean
       (class=conversion #args=1): Convert int/float/bool/string to boolean.

   float
       (class=conversion #args=1): Convert int/float/bool/string to float.

   fmtnum
       (class=conversion #args=2): Convert int/float/bool to string using
       printf-style format string, e.g. '$s = fmtnum($n, "%06lld")'. WARNING: Miller numbers
       are all long long or double. If you use formats like %d or %f, behavior is undefined.

   hexfmt
       (class=conversion #args=1): Convert int to string, e.g. 255 to "0xff".

   int
       (class=conversion #args=1): Convert int/float/bool/string to int.

   string
       (class=conversion #args=1): Convert int/float/bool/string to string.

   typeof
       (class=conversion #args=1): Convert argument to type of argument (e.g.
       MT_STRING). For debug.

   depth
       (class=maps #args=1): Prints maximum depth of hashmap: ''. Scalars have depth 0.

   haskey
       (class=maps #args=2): True/false if map has/hasn't key, e.g. 'haskey($*, "a")' or
       'haskey(mymap, mykey)'. Error if 1st argument is not a map.

   joink
       (class=maps #args=2): Makes string from map keys. E.g. 'joink($*, ",")'.

   joinkv
       (class=maps #args=3): Makes string from map key-value pairs. E.g. 'joinkv(@v[2], "=", ",")'

   joinv
       (class=maps #args=2): Makes string from map keys. E.g. 'joinv(mymap, ",")'.

   leafcount
       (class=maps #args=1): Counts total number of terminal values in hashmap. For single-level maps,
       same as length.

   length
       (class=maps #args=1): Counts number of top-level entries in hashmap. Scalars have length 1.

   mapdiff
       (class=maps variadic): With 0 args, returns empty map. With 1 arg, returns copy of arg.
       With 2 or more, returns copy of arg 1 with all keys from any of remaining argument maps removed.

   mapexcept
       (class=maps variadic): Returns a map with keys from remaining arguments, if any, unset.
       E.g. 'mapexcept({1:2,3:4,5:6}, 1, 5, 7)' is '{3:4}'.

   mapselect
       (class=maps variadic): Returns a map with only keys from remaining arguments set.
       E.g. 'mapselect({1:2,3:4,5:6}, 1, 5, 7)' is '{1:2,5:6}'.

   mapsum
       (class=maps variadic): With 0 args, returns empty map. With >= 1 arg, returns a map with
       key-value pairs from all arguments. Rightmost collisions win, e.g. 'mapsum({1:2,3:4},{1:5})' is '{1:5,3:4}'.

   splitkv
       (class=maps #args=3): Splits string by separators into map with type inference.
       E.g. 'splitkv("a=1,b=2,c=3", "=", ",")' gives '{"a" : 1, "b" : 2, "c" : 3}'.

   splitkvx
       (class=maps #args=3): Splits string by separators into map without type inference (keys and
       values are strings). E.g. 'splitkv("a=1,b=2,c=3", "=", ",")' gives
       '{"a" : "1", "b" : "2", "c" : "3"}'.

   splitnv
       (class=maps #args=2): Splits string by separator into integer-indexed map with type inference.
       E.g. 'splitnv("a,b,c" , ",")' gives '{1 : "a", 2 : "b", 3 : "c"}'.

   splitnvx
       (class=maps #args=2): Splits string by separator into integer-indexed map without type
       inference (values are strings). E.g. 'splitnv("4,5,6" , ",")' gives '{1 : "4", 2 : "5", 3 : "6"}'.

KEYWORDS FOR PUT AND FILTER
   all
       all: used in "emit", "emitp", and "unset" as a synonym for @*

   begin
       begin: defines a block of statements to be executed before input records
       are ingested. The body statements must be wrapped in curly braces.
       Example: 'begin { @count = 0 }'

   bool
       bool: declares a boolean local variable in the current curly-braced scope.
       Type-checking happens at assignment: 'bool b = 1' is an error.

   break
       break: causes execution to continue after the body of the current
       for/while/do-while loop.

   call
       call: used for invoking a user-defined subroutine.
       Example: 'subr s(k,v) { print k . " is " . v} call s("a", $a)'

   continue
       continue: causes execution to skip the remaining statements in the body of
       the current for/while/do-while loop. For-loop increments are still applied.

   do
       do: with "while", introduces a do-while loop. The body statements must be wrapped
       in curly braces.

   dump
       dump: prints all currently defined out-of-stream variables immediately
     to stdout as JSON.

     With >, >>, or |, the data do not become part of the output record stream but
     are instead redirected.

     The > and >> are for write and append, as in the shell, but (as with awk) the
     file-overwrite for > is on first write, not per record. The | is for piping to
     a process which will process the data. There will be one open file for each
     distinct file name (for > and >>) or one subordinate process for each distinct
     value of the piped-to command (for |). Output-formatting flags are taken from
     the main command line.

     Example: mlr --from f.dat put -q '@v[NR]=$*; end { dump }'
     Example: mlr --from f.dat put -q '@v[NR]=$*; end { dump >  "mytap.dat"}'
     Example: mlr --from f.dat put -q '@v[NR]=$*; end { dump >> "mytap.dat"}'
     Example: mlr --from f.dat put -q '@v[NR]=$*; end { dump | "jq .[]"}'

   edump
       edump: prints all currently defined out-of-stream variables immediately
     to stderr as JSON.

     Example: mlr --from f.dat put -q '@v[NR]=$*; end { edump }'

   elif
       elif: the way Miller spells "else if". The body statements must be wrapped
       in curly braces.

   else
       else: terminates an if/elif/elif chain. The body statements must be wrapped
       in curly braces.

   emit
       emit: inserts an out-of-stream variable into the output record stream. Hashmap
     indices present in the data but not slotted by emit arguments are not output.

     With >, >>, or |, the data do not become part of the output record stream but
     are instead redirected.

     The > and >> are for write and append, as in the shell, but (as with awk) the
     file-overwrite for > is on first write, not per record. The | is for piping to
     a process which will process the data. There will be one open file for each
     distinct file name (for > and >>) or one subordinate process for each distinct
     value of the piped-to command (for |). Output-formatting flags are taken from
     the main command line.

     You can use any of the output-format command-line flags, e.g. --ocsv, --ofs,
     etc., to control the format of the output if the output is redirected. See also mlr -h.

     Example: mlr --from f.dat put 'emit >  "/tmp/data-".$a, $*'
     Example: mlr --from f.dat put 'emit >  "/tmp/data-".$a, mapexcept($*, "a")'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit @sums'
     Example: mlr --from f.dat put --ojson '@sums[$a][$b]+=$x; emit > "tap-".$a.$b.".dat", @sums'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit @sums, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit >  "mytap.dat", @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit >> "mytap.dat", @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit | "gzip > mytap.dat.gz", @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit > stderr, @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emit | "grep somepattern", @*, "index1", "index2"'

     Please see http://johnkerl.org/miller/doc for more information.

   emitf
       emitf: inserts non-indexed out-of-stream variable(s) side-by-side into the
     output record stream.

     With >, >>, or |, the data do not become part of the output record stream but
     are instead redirected.

     The > and >> are for write and append, as in the shell, but (as with awk) the
     file-overwrite for > is on first write, not per record. The | is for piping to
     a process which will process the data. There will be one open file for each
     distinct file name (for > and >>) or one subordinate process for each distinct
     value of the piped-to command (for |). Output-formatting flags are taken from
     the main command line.

     You can use any of the output-format command-line flags, e.g. --ocsv, --ofs,
     etc., to control the format of the output if the output is redirected. See also mlr -h.

     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf @a'
     Example: mlr --from f.dat put --oxtab '@a=$i;@b+=$x;@c+=$y; emitf > "tap-".$i.".dat", @a'
     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf @a, @b, @c'
     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf > "mytap.dat", @a, @b, @c'
     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf >> "mytap.dat", @a, @b, @c'
     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf > stderr, @a, @b, @c'
     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf | "grep somepattern", @a, @b, @c'
     Example: mlr --from f.dat put '@a=$i;@b+=$x;@c+=$y; emitf | "grep somepattern > mytap.dat", @a, @b, @c'

     Please see http://johnkerl.org/miller/doc for more information.

   emitp
       emitp: inserts an out-of-stream variable into the output record stream.
     Hashmap indices present in the data but not slotted by emitp arguments are
     output concatenated with ":".

     With >, >>, or |, the data do not become part of the output record stream but
     are instead redirected.

     The > and >> are for write and append, as in the shell, but (as with awk) the
     file-overwrite for > is on first write, not per record. The | is for piping to
     a process which will process the data. There will be one open file for each
     distinct file name (for > and >>) or one subordinate process for each distinct
     value of the piped-to command (for |). Output-formatting flags are taken from
     the main command line.

     You can use any of the output-format command-line flags, e.g. --ocsv, --ofs,
     etc., to control the format of the output if the output is redirected. See also mlr -h.

     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp @sums'
     Example: mlr --from f.dat put --opprint '@sums[$a][$b]+=$x; emitp > "tap-".$a.$b.".dat", @sums'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp @sums, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp >  "mytap.dat", @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp >> "mytap.dat", @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp | "gzip > mytap.dat.gz", @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp > stderr, @*, "index1", "index2"'
     Example: mlr --from f.dat put '@sums[$a][$b]+=$x; emitp | "grep somepattern", @*, "index1", "index2"'

     Please see http://johnkerl.org/miller/doc for more information.

   end
       end: defines a block of statements to be executed after input records
       are ingested. The body statements must be wrapped in curly braces.
       Example: 'end { emit @count }'
       Example: 'end { eprint "Final count is " . @count }'

   eprint
       eprint: prints expression immediately to stderr.
     Example: mlr --from f.dat put -q 'eprint "The sum of x and y is ".($x+$y)'
     Example: mlr --from f.dat put -q 'for (k, v in $*) { eprint k . " => " . v }'
     Example: mlr --from f.dat put  '(NR % 1000 == 0) { eprint "Checkpoint ".NR}'

   eprintn
       eprintn: prints expression immediately to stderr, without trailing newline.
     Example: mlr --from f.dat put -q 'eprintn "The sum of x and y is ".($x+$y); eprint ""'

   false
       false: the boolean literal value.

   filter
       filter: includes/excludes the record in the output record stream.

     Example: mlr --from f.dat put 'filter (NR == 2 || $x > 5.4)'

     Instead of put with 'filter false' you can simply use put -q.  The following
     uses the input record to accumulate data but only prints the running sum
     without printing the input record:

     Example: mlr --from f.dat put -q '@running_sum += $x * $y; emit @running_sum'

   float
       float: declares a floating-point local variable in the current curly-braced scope.
       Type-checking happens at assignment: 'float x = 0' is an error.

   for
       for: defines a for-loop using one of three styles. The body statements must
       be wrapped in curly braces.
       For-loop over stream record:
     Example:  'for (k, v in $*) { ... }'
       For-loop over out-of-stream variables:
     Example: 'for (k, v in @counts) { ... }'
     Example: 'for ((k1, k2), v in @counts) { ... }'
     Example: 'for ((k1, k2, k3), v in @*) { ... }'
       C-style for-loop:
     Example:  'for (var i = 0, var b = 1; i < 10; i += 1, b *= 2) { ... }'

   func
       func: used for defining a user-defined function.
       Example: 'func f(a,b) { return sqrt(a**2+b**2)} $d = f($x, $y)'

   if
       if: starts an if/elif/elif chain. The body statements must be wrapped
       in curly braces.

   in
       in: used in for-loops over stream records or out-of-stream variables.

   int
       int: declares an integer local variable in the current curly-braced scope.
       Type-checking happens at assignment: 'int x = 0.0' is an error.

   map
       map: declares an map-valued local variable in the current curly-braced scope.
       Type-checking happens at assignment: 'map b = 0' is an error. map b = {} is
       always OK. map b = a is OK or not depending on whether a is a map.

   num
       num: declares an int/float local variable in the current curly-braced scope.
       Type-checking happens at assignment: 'num b = true' is an error.

   print
       print: prints expression immediately to stdout.
     Example: mlr --from f.dat put -q 'print "The sum of x and y is ".($x+$y)'
     Example: mlr --from f.dat put -q 'for (k, v in $*) { print k . " => " . v }'
     Example: mlr --from f.dat put  '(NR % 1000 == 0) { print > stderr, "Checkpoint ".NR}'

   printn
       printn: prints expression immediately to stdout, without trailing newline.
     Example: mlr --from f.dat put -q 'printn "."; end { print "" }'

   return
       return: specifies the return value from a user-defined function.
       Omitted return statements (including via if-branches) result in an absent-null
       return value, which in turns results in a skipped assignment to an LHS.

   stderr
       stderr: Used for tee, emit, emitf, emitp, print, and dump in place of filename
     to print to standard error.

   stdout
       stdout: Used for tee, emit, emitf, emitp, print, and dump in place of filename
     to print to standard output.

   str
       str: declares a string local variable in the current curly-braced scope.
       Type-checking happens at assignment.

   subr
       subr: used for defining a subroutine.
       Example: 'subr s(k,v) { print k . " is " . v} call s("a", $a)'

   tee
       tee: prints the current record to specified file.
     This is an immediate print to the specified file (except for pprint format
     which of course waits until the end of the input stream to format all output).

     The > and >> are for write and append, as in the shell, but (as with awk) the
     file-overwrite for > is on first write, not per record. The | is for piping to
     a process which will process the data. There will be one open file for each
     distinct file name (for > and >>) or one subordinate process for each distinct
     value of the piped-to command (for |). Output-formatting flags are taken from
     the main command line.

     You can use any of the output-format command-line flags, e.g. --ocsv, --ofs,
     etc., to control the format of the output. See also mlr -h.

     emit with redirect and tee with redirect are identical, except tee can only
     output $*.

     Example: mlr --from f.dat put 'tee >  "/tmp/data-".$a, $*'
     Example: mlr --from f.dat put 'tee >> "/tmp/data-".$a.$b, $*'
     Example: mlr --from f.dat put 'tee >  stderr, $*'
     Example: mlr --from f.dat put -q 'tee | "tr [a-z\] [A-Z\]", $*'
     Example: mlr --from f.dat put -q 'tee | "tr [a-z\] [A-Z\] > /tmp/data-".$a, $*'
     Example: mlr --from f.dat put -q 'tee | "gzip > /tmp/data-".$a.".gz", $*'
     Example: mlr --from f.dat put -q --ojson 'tee | "gzip > /tmp/data-".$a.".gz", $*'

   true
       true: the boolean literal value.

   unset
       unset: clears field(s) from the current record, or an out-of-stream or local variable.

     Example: mlr --from f.dat put 'unset $x'
     Example: mlr --from f.dat put 'unset $*'
     Example: mlr --from f.dat put 'for (k, v in $*) { if (k =~ "a.*") { unset $[k] } }'
     Example: mlr --from f.dat put '...; unset @sums'
     Example: mlr --from f.dat put '...; unset @sums["green"]'
     Example: mlr --from f.dat put '...; unset @*'

   var
       var: declares an untyped local variable in the current curly-braced scope.
       Examples: 'var a=1', 'var xyz=""'

   while
       while: introduces a while loop, or with "do", introduces a do-while loop.
       The body statements must be wrapped in curly braces.

   ENV
       ENV: access to environment variables by name, e.g. '$home = ENV["HOME"]'

   FILENAME
       FILENAME: evaluates to the name of the current file being processed.

   FILENUM
       FILENUM: evaluates to the number of the current file being processed,
       starting with 1.

   FNR
       FNR: evaluates to the number of the current record within the current file
       being processed, starting with 1. Resets at the start of each file.

   IFS
       IFS: evaluates to the input field separator from the command line.

   IPS
       IPS: evaluates to the input pair separator from the command line.

   IRS
       IRS: evaluates to the input record separator from the command line,
       or to LF or CRLF from the input data if in autodetect mode (which is
       the default).

   M_E
       M_E: the mathematical constant e.

   M_PI
       M_PI: the mathematical constant pi.

   NF
       NF: evaluates to the number of fields in the current record.

   NR
       NR: evaluates to the number of the current record over all files
       being processed, starting with 1. Does not reset at the start of each file.

   OFS
       OFS: evaluates to the output field separator from the command line.

   OPS
       OPS: evaluates to the output pair separator from the command line.

   ORS
       ORS: evaluates to the output record separator from the command line,
       or to LF or CRLF from the input data if in autodetect mode (which is
       the default).

AUTHOR
       Miller is written by John Kerl <kerl.john.r@gmail.com>.

       This manual page has been composed from Miller's help output by Eric
       MSP Veith <eveith@veith-m.de>.

SEE ALSO
       awk(1), sed(1), cut(1), join(1), sort(1), RFC 4180: Common Format and
       MIME Type for Comma-Separated Values (CSV) Files, the miller website
       http://johnkerl.org/miller/doc



                              2020-10-07                         MILLER(1)