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 and JSON. (Miller can handle positionally-indexed data as a special case.) This manpage documents Miller v4.2.0.

EXAMPLES

COMMAND-LINE SYNTAX

mlr --csv cut -f hostname,uptime mydata.csv
mlr --csv --rs lf filter '$status != "down" && $upsec >= 10000' *.csv
mlr --nidx put '$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 $*) {
    if (isnumeric(v) && k =~ "^[t-z].*$") {
      $sum += v; $count += 1
    }
  }
  $mean = $sum / $count # no assignment if count unset'
mlr --from infile.dat put -f analyze.mlr

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              |
  +---------------------+

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.
  --list-all-verbs or -l List only verb names.
  --help-all-verbs       Show help on all verbs.

VERB LIST

 bar bootstrap cat check count-distinct cut decimate filter grep group-by
 group-like having-fields head histogram join label merge-fields nest put
 regularize rename reorder repeat reshape sample shuffle sec2gmt sort stats1
 stats2 step tac tail top uniq

FUNCTION LIST

 + + - - * / // % ** | ^ & ~ << >> == != =~ !=~ > >= < <= && || ^^ ! ? : isnull
 isnotnull isabsent ispresent isempty isnotempty isnumeric isint isfloat isbool
 isstring boolean float fmtnum hexfmt int string typeof . gsub strlen sub
 tolower toupper 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 urand32
 urandint dhms2fsec dhms2sec fsec2dhms fsec2hms gmt2sec hms2fsec hms2sec
 sec2dhms sec2gmt sec2hms strftime strptime systime
Please use "mlr --help-function {function name}" for function-specific help.
Please use "mlr --help-all-functions" or "mlr -f" for help on all functions.
Please use "mlr --help-all-keywords" or "mlr -k" for help on all keywords.

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).
  --icsv    --ocsv    --csv       Comma-separated value (or tab-separated
                                  with --fs tab, etc.)
  --ipprint --opprint --pprint    Pretty-printed tabular (produces no
                                  output until all input is in).
                      --right     Right-justifies all fields for PPRINT 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 [{...},{...}].
                      --jvstack   Put one key-value pair per line for JSON
                                  output.
                      --jlistwrap Wrap JSON output in outermost [ ].
                      --jquoteall Quote map keys 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 "mlr --csv --rs lf" FOR NATIVE UN*X (LINEFEED-TERMINATED) CSV FILES.

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
  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}

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:
  * 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.
  * 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.
  * DKVP, NIDX, CSVLITE, PPRINT, and XTAB formats are intended to handle
    platform-native text data. In particular, this means LF line-terminators
    by default on Linux/OSX. You can use "--dkvp --rs crlf" for
    CRLF-terminated DKVP files, and so on.
  * CSV is intended to handle RFC-4180-compliant data. In particular, this means
    it uses CRLF line-terminators by default. You can use "--csv --rs lf" for
    Linux-native CSV files.
  * All RS/FS/PS options are ignored for JSON format: JSON doesn't allow
    changing these.
  * 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
      dkvp         \n       ,        =
      json         (N/A)    (N/A)    (N/A)
      nidx         \n       space    (N/A)
      csv          \r\n     ,        (N/A)
      csvlite      \n       ,        (N/A)
      pprint       \n       space    (N/A)
      xtab         (N/A)    \n       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.
  --headerless-csv-output   Print only CSV data lines.

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

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).

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

VERBS

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
-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.

count-distinct

Usage: mlr count-distinct [options]
-f {a,b,c}    Field names for distinct count.
-n            Show only the number of distinct values.
Prints number of records having distinct values for specified field names.
Same as uniq -c.

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.

filter

Usage: mlr filter [options] {expression}
Prints records for which {expression} evaluates to true.
Options:
-v: First prints the AST (abstract syntax tree) for the expression, which gives
    full transparency on the precedence and associativity rules of Miller's
    grammar.
-S: Keeps field values, or literals in the expression, as strings with no type 
    inference to int or float.
-F: Keeps field values, or literals in the expression, as strings or floats
    with no inference to int.
-x: Prints records for which {expression} evaluates to false.
-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.
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. '${field.name}'. Miller built-in variables are
NF NR FNR FILENUM FILENAME PI E, and ENV["namegoeshere"] to access environment
variables. The environment-variable name may be an expression, e.g. a field value.
Use # to comment to end of line.
Examples:
  mlr filter 'log10($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 '
    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 also "mlr grep" which is
useful when you don't yet know which field name(s) you're looking for.

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.

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.
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)
  -u           Enable unsorted input. In this case, the entire left file will
               be loaded into memory. Without -u, records must be sorted
               lexically by their join-field names, else not all records will
               be paired.
  --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
  --use-mmap
  --no-mmap
Please use "mlr --usage-separator-options" for information on specifying separators.
Please see http://johnkerl.org/miller/doc/reference.html 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"

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
  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.
-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.
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".

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.
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.

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.).
Options:
-v: First prints the AST (abstract syntax tree) for the expression, which gives
    full transparency on the precedence and associativity rules of Miller's
    grammar.
-q: Does not include the modified record in the output stream. Useful for when
    all desired output is in begin and/or end blocks.
-S: Keeps field values, or literals in the expression, as strings with no type 
    inference to int or float.
-F: Keeps field values, or literals in the expression, as strings or floats
    with no inference to int.
--oflatsep {string}: Separator to use when flattening multi-level @-variables
    to output records for emit. Default ":".
-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.
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. '${field.name}'. Miller built-in variables are
NF NR FNR FILENUM FILENAME PI E, and ENV["namegoeshere"] to access environment
variables. The environment-variable name may be an expression, e.g. a field value.
Use # to comment to end of line.
Examples:
  mlr put '$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 'isnull(@xmax) || $x > @xmax {@xmax=$x; @recmax=$*}; end {emit @recmax}'
  mlr put '
    $x = 1;
   #$y = 2;
    $z = 3
  '
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.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

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 -f old_name,new_name'
mlr rename -f 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.

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.

sec2gmt

Usage: mlr sec2gmt {comma-separated list of field names}
Replaces a numeric field representing seconds since the epoch with the
corresponding GMT timestamp. 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)'

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}  Numerical ascending; nulls sort last
  -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.
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
  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
-g {d,e,f}  Optional group-by-field names
-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
Notes:
* p50 is a synonym for median.
* min and max output the same results as p0 and p100, respectively, but use
  less memory.
* 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
  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.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.

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.
Prints the n records with smallest/largest values at specified fields,
optionally by category.

uniq

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

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): 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.

==

(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.

isnull

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

isnotnull

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

isabsent

(class=conversion #args=1): False if field is present in input, false otherwise

ispresent

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

isempty

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

isnotempty

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

isnumeric

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

isint

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

isfloat

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

isbool

(class=conversion #args=1): True if field is present with boolean value

isstring

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

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. "%06lld".

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.

.

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

gsub

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

strlen

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

sub

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

tolower

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

toupper

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

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 #args=2): max of two numbers; null loses

mexp

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

min

(class=math #args=2): min of two 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 on the unit interval.
Int-valued example: '$n=floor(20+urand()*11)'.

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.

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".

sec2hms

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

strftime

(class=time #args=2): Formats seconds since epoch (integer part)
as timestamp, e.g.
strftime(1440768801.7,"%Y-%m-%dT%H:%M:%SZ") = "2015-08-28T13:33:21Z".

strptime

(class=time #args=2): Parses timestamp as integer seconds since epoch,
e.g. strptime("2015-08-28T13:33:21Z","%Y-%m-%dT%H:%M:%SZ") = 1440768801.

systime

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

KEYWORDS FOR PUT

filter

filter: includes/excludes the record in the output record
  stream.
  Example: mlr 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:
  mlr put -q '@running_sum += $x * $y; emit @running_sum'.

unset

unset: clears field(s) from the current record, or an out-of-stream variable.
  Example: mlr put 'unset $x'
  Example: mlr put 'unset $*'
  Example: mlr put 'for (k, v in $*) { if (k =~ "a.*") { unset $[k] } }'
  Example: mlr put '...; unset @sums'
  Example: mlr put '...; unset @sums["green"]'
  Example: mlr put '...; unset @*'

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.
  Example: mlr put '... ; emit @sums'
  Example: mlr put '... ; emit @sums, "index1", "index2"'
  Example: mlr put '... ; emit @*, "index1", "index2"'
  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 ":".
  Example: mlr put '... ; emitp @sums'
  Example: mlr put '... ; emitp @sums, "index1", "index2"'
  Example: mlr put '... ; emitp @*, "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.
  Example: mlr put '... ; emit @a'
  Example: mlr put '... ; emit @a, @b, @c'
  Please see http://johnkerl.org/miller/doc for more information.

dump

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

edump

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

print

print: prints expression immediately to stdout.
  Example: mlr put -q 'print "The sum of x and y is ".string($x+$y)'.
  Example: mlr put -q 'for (k, v in $*) { print string(k) . " => " . string(v) }'.

eprint

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

AUTHOR

Miller is written by John Kerl <[email protected]>.

This manual page has been composed from Miller's help output by Eric MSP Veith <[email protected]>.