DATAMASH(1)

NAME
datamash - command-line calculations

SYNOPSIS
datamash [OPTION] op [fld] [op fld ...]

DESCRIPTION
Performs numeric/string operations on input from stdin.

'op' is the operation to perform. If a primary operation is used, it must be listed first, optionally followed by other operations. 'fld' is the input field to use. 'fld' can be a number (1=first field), or a field name when using the -H or --header-in options. Multiple fields can be listed with a comma (e.g. 1,6,8). A range of fields can be listed with a dash (e.g. 2-8). Use colons for operations which require a pair of fields (e.g. 'pcov 2:6').

  Primary operations:

    groupby, crosstab, transpose, reverse, check

  Line-Filtering operations:

    rmdup

  Per-Line operations:

    base64, debase64, md5, sha1, sha224, sha256, sha384, sha512, bin, strbin, round, floor, ceil, trunc, frac, dirname, basename, barename, extname, getnum, cut

  Numeric Grouping operations:

    sum, min, max, absmin, absmax, range

  Textual/Numeric Grouping operations:

    count, first, last, rand, unique, collapse, countunique

  Statistical Grouping operations:

    mean, geomean, harmmean, trimmean, median, q1, q3, iqr, perc, mode, antimode, pstdev, sstdev, pvar, svar, ms, rms, mad, madraw, pskew, sskew, pkurt, skurt, dpo, jarque, scov, pcov, spearson, ppearson, dotprod

OPTIONS

  Grouping Options:

-C, --skip-comments
    skip comment lines (starting with '#' or ';' and optional whitespace)

-f, --full
    print entire input line before op results (default: print only the grouped keys)

    This option is only sensible for linewise operations. Other uses are deprecated and will be removed in a future version of GNU Datamash.

-g, --group=X[,Y,Z]
    group via fields X,[Y,Z]; equivalent to primary operation 'groupby'

--header-in
    first input line is column headers

--header-out
    print column headers as first line

-H, --headers
    same as '--header-in --header-out'

--vnlog
    Reads and writes data in the vnlog format. Implies -C -H -W

-i, --ignore-case
    ignore upper/lower case when comparing text; this affects grouping, and string operations

-s, --sort
    sort the input before grouping; this removes the need to manually pipe the input through 'sort'

-S, --seed
    set a seed for operations that use randomization

-c, --collapse-delimiter=X
    use X to separate elements in collapse and unique lists (default: comma)

  File Operation Options:

--no-strict
    allow lines with varying number of fields

--filler=X
    fill missing values with X (default N/A)

  General Options:

-t, --field-separator=X
    use X instead of TAB as field delimiter

--format=FORMAT
    print numeric values with printf style floating-point FORMAT.

--output-delimiter=X
    use X instead as output field delimiter (default: use same delimiter as -t/-W)

--narm
    skip NA/NaN values

-R, --round=N
    round numeric output to N decimal places

-W, --whitespace
    use whitespace (one or more spaces and/or tabs) for field delimiters

-z, --zero-terminated
    end lines with 0 byte, not newline

--sort-cmd=/path/to/sort
    Alternative sort(1) to use.

-h, --help
    display this help and exit

-V, --version
    output version information and exit

AVAILABLE OPERATIONS

  Primary Operations
Primary operations affect the way the file is processed. If used, the primary operation must be listed first. If primary operation is not listed the entire file is processed - either line-by-line (for 'per-line' operations) or all lines as one group (for grouping operations). See Examples section below.

groupby X,Y,... op fld ...
    group the file by given fields. Equivalent to option '-g'. For each group perform operation op on field fld.

crosstab X,Y [op fld ...]
    cross-tabulate a file by two fields (cross-tabulation is also known as pivot tables). If no operation is specified, counts how many incidents exist of X,Y.

transpose
    transpose rows, columns of the input file

reverse
    reverse field order in each line

check [N lines] [N fields]
    verify the input file has same number of fields in all lines, or the expected number of lines/fields. number of lines and fields are printed to STDOUT. Exits with non-zero code and prints the offending line if there's a mismatch in the number of lines/ fields.

  Line-Filtering operations

rmdup
    remove lines with duplicated key value

  Per-Line operations

base64
    Encode the field as base64

debase64
    Decode the field as base64, exit with error if invalid base64 string

md5/sha1/sha224/sha256/sha384/sha512
    Calculate md5/sha1/sha224/sha256/sha384/sha512 hash of the field value

bin[:BUCKET-SIZE]
    bin numeric values into buckets of size BUCKET-SIZE (defaults to 100).

strbin[:BUCKET-SIZE]
    hashes the input and returns a numeric integer value between zero and BUCKET-SIZE (defaults to 10).

round/floor/ceil/trunc/frac
    numeric rounding operations. round (round half away from zero), floor (round down), ceil (ceiling, round up), trunc (truncate, round towards zero), frac (fraction, return fraction part of a decimal-point value).

dirname/basename
    extract the directory name and the base file name from a given string (same as to dirname(1) and basename(1)).

extname
    extract the extension of the file name (without the '.').

barename
    extract the base file name without the extension.

getnum[:TYPE]
    extract a number from the field. TYPE is optional single letter option n/i/d/p/h/o (see examples below).

cut/echo
    copy input field to output field (similar to cut(1)). The echo command is simply an alias to cut.

  Numeric Grouping operations

sum sum the of values

min minimum value

max maximum value

absmin
    minimum of the absolute values

absmax
    maximum of the absolute values

range
    the values range (max-min)

  Textual/Numeric Grouping operations

count
    count number of elements in the group

first
    the first value of the group

last
    the last value of the group

rand
    one random value from the group

unique/uniq
    comma-separated sorted list of unique values The uniq command is simply an alias to unique.

collapse
    comma-separated list of all input values

countunique
    number of unique/distinct values

  Statistical Grouping operations
A p/s prefix indicates the variant: population or sample. Typically, the sample variant is equivalent with GNU R's internal functions (e.g datamash's sstdev operation is equivalent to R's sd() function).

mean
    mean of the values

geomean
    geometric mean of the values

harmmean
    harmonic mean of the values

trimmean[:PERCENT]
    trimmed mean of the values. PERCENT should be between 0 and 0.5. (trimmean:0 is equivalent to mean. trimmean:0.5 is equivalent to median).

ms  mean square of the values

rms root mean square of the values

median
    median value

q1  1st quartile value

q3  3rd quartile value

iqr inter-quartile range

perc[:PERCENTILE]
    percentile value PERCENTILE (defaults to 95).

mode
    mode value (most common value)

antimode
    anti-mode value (least common value)

pstdev/sstdev
    population/sample standard deviation

pvar/svar
    population/sample variance

mad median absolute deviation, scaled by constant 1.4826 for normal distributions

madraw
    median absolute deviation, unscaled

pskew/sskew
    skewness of the group
      values x reported by 'sskew' and 'pskew' operations:
              x > 0       -  positively skewed / skewed right
          0 > x           -  negatively skewed / skewed left
              x > 1       -  highly skewed right
          1 > x >  0.5    -  moderately skewed right
        0.5 > x > -0.5    -  approximately symmetric
       -0.5 > x > -1      -  moderately skewed left
         -1 > x           -  highly skewed left

pkurt/skurt
    excess Kurtosis of the group

jarque/dpo
    p-value of the Jarque-Beta (jarque) and D'Agostino-Pearson Omnibus (dpo) tests for normality:
       null hypothesis is normality;
       low p-Values indicate non-normal data;
       high p-Values indicate null-hypothesis cannot be rejected.

pcov/scov [X:Y]
    covariance of fields X and Y

ppearson/spearson [X:Y]
    Pearson product-moment correlation coefficient [Pearson's R] of fields X and Y

dotprod [X:Y]
    Scalar product (aka dot product or Euclidean inner product) of fields X and Y

EXAMPLES

  Basic usage
Print the sum and the mean of values from field 1:

    $ seq 10 | datamash sum 1 mean 1
    55  5.5

Group input based on field 1, and sum values (per group) on field 2:

    $ cat example.txt
    A  10
    A  5
    B  9
    B  11
    $ datamash -g 1 sum 2 < example.txt
    A  15
    B  20
    $ datamash groupby 1 sum 2 < example.txt
    A  15
    B  20

Unsorted input must be sorted (with '-s'):

    $ cat example.txt
    A  10
    C  4
    B  9
    C  1
    A  5
    B  11
    $ datamash -s -g1 sum 2 < example.txt
    A  15
    B  20
    C  5

Which is equivalent to:

    $ cat example.txt | sort -k1,1 | datamash -g 1 sum 2

  Header lines

Use -H (--headers) if the input file has a header line:

    # Given a file with student name, field, test score...
    $ head -n5 scores_h.txt
    Name           Major            Score
    Shawn          Engineering      47
    Caleb          Business         87
    Christian      Business         88
    Derek          Arts             60
    # Calculate the mean and standard deviation for each major
    $ datamash --sort --headers --group 2 mean 3 pstdev 3 < scores_h.txt
     (or use short form)
    $ datamash -sH -g2 mean 3 pstdev 3 < scores_h.txt
     (or use named fields)
    $ datamash -sH -g Major mean Score pstdev Score < scores_h.txt
    GroupBy(Major)    mean(Score)   pstdev(Score)
    Arts              68.9          10.1
    Business          87.3           4.9
    Engineering       66.5          19.1
    Health-Medicine   90.6           8.8
    Life-Sciences     55.3          19.7
    Social-Sciences   60.2          16.6

Field names must be escaped with a backslash if they start with a digit or contain special characters (dash/minus, colons, commas). Note the interplay between escaping with backslash and shell quoting. The following equivalent command sum the values of a field named "FOO-BAR":

    $ datamash -H sum FOO\\-BAR < input.txt
    $ datamash -H sum 'FOO\-BAR' < input.txt
    $ datamash -H sum "FOO\\-BAR" < input.txt

  Skipping comment lines
Use -C (--skip-comments) to skip lines starting with '#' or ';' characters (and optional whitespace before them):

    $ cat in.txt
     #foo   3
    bar     5
    ;baz    7
    $ datamash sum 2 < in.txt
    15
    $ datamash -C sum 2 < in.txt
    5

  Multiple fields
Use comma or dash to specify multiple fields. The following are equivalent:
    $ seq 9 | paste - - -
    1   2   3
    4   5   6
    7   8   9
    $ seq 9 | paste - - - | datamash sum 1 sum 2 sum 3
    12  15  18
    $ seq 9 | paste - - - | datamash sum 1,2,3
    12  15  18
    $ seq 9 | paste - - - | datamash sum 1-3
    12  15  18

  Rounding
The following demonstrate the different rounding operations:
$ ( echo X ; seq -1.25 0.25 1.25 ) \
      | datamash --full -H round 1 ceil 1 floor 1 trunc 1 frac 1
  X     round(X)  ceil(X)  floor(X)  trunc(X)   frac(X)
-1.25   -1        -1       -2        -1         -0.25
-1.00   -1        -1       -1        -1          0
-0.75   -1         0       -1         0         -0.75
-0.50   -1         0       -1         0         -0.5
-0.25    0         0       -1         0         -0.25
 0.00    0         0        0         0          0
 0.25    0         1        0         0          0.25
 0.50    1         1        0         0          0.5
 0.75    1         1        0         0          0.75
 1.00    1         1        1         1          0
 1.25    1         2        1         1          0.25

  Reversing fields

    $ seq 6 | paste - - | datamash reverse
    2    1
    4    3
    6    5

  Transposing a file

    $ seq 6 | paste - - | datamash transpose
    1    3    5
    2    4    6

  Removing Duplicated lines
Remove lines with duplicate key value from field 1 (Unlike first,last operations, rmdup is much faster and does not require sorting the file with -s):

    # Given a list of files and sample IDs:
    $ cat INPUT
    SampleID  File
    2         cc.txt
    3         dd.txt
    1         ab.txt
    2         ee.txt
    3         ff.txt
    # Remove lines with duplicated Sample-ID (field 1):
    $ datamash rmdup 1 < INPUT
    # or use named field:
    $ datamash -H rmdup SampleID < INPUT
    SampleID  File
    2         cc.txt
    3         dd.txt
    1         ab.txt

  Checksums
Calculate the sha1 hash value of each TXT file, after calculating the sha1 value of each file's content:

    $ sha1sum *.txt | datamash -Wf sha1 2

  Check file structure
Check the structure of the input file: ensure all lines have the same number of fields, or expected number of lines/fields:

    $ seq 10 | paste - - | datamash check && echo ok || echo fail
    5 lines, 2 fields
    ok
    $ seq 13 | paste - - - | datamash check && echo ok || echo fail
    line 4 (3 fields):
      10  11  12
    line 5 (2 fields):
      13
    datamash: check failed: line 5 has 2 fields (previous line had 3)
    fail
    $ seq 10 | paste - - | datamash check 2 fields 5 lines
    5 lines, 2 fields
    $ seq 10 | paste - - | datamash check 4 fields
    line 1 (2 fields):
      1     2
    datamash: check failed: line 1 has 2 fields (expecting 4)
    $ seq 10 | paste - - | datamash check 7 lines
    datamash: check failed: input had 5 lines (expecting 7)

  Cross-Tabulation
Cross-tabulation compares the relationship between two fields. Given the following input file:
    $ cat input.txt
    a    x    3
    a    y    7
    b    x    21
    a    x    40

Show cross-tabulation between the first field (a/b) and the second field (x/y) - counting how many times each pair appears (note: sorting is required):

    $ datamash -s crosstab 1,2 < input.txt
         x    y
    a    2    1
    b    1    N/A

An optional grouping operation can be used instead of counting:

    $ datamash -s crosstab 1,2 sum 3 < input.txt
         x    y
    a    43   7
    b    21   N/A
    $ datamash -s crosstab 1,2 unique 3 < input.txt
         x    y
    a    3,40 7
    b    21   N/A

  Binning numeric values
Bin input values into buckets of size 5:

    $  ( echo X ; seq -10 2.5 10 ) \
          | datamash -H --full bin:5 1
        X  bin(X)
    -10.0    -10
     -7.5    -10
     -5.0     -5
     -2.5     -5
      0.0      0
      2.5      0
      5.0      5
      7.5      5
     10.0     10

  Binning string values
Hash any input value into a numeric integer. A typical usage would be to split an input file into N chunks, ensuring that all values of a certain key will be stored in the same chunk:

    $ cat input.txt
    PatientA   10
    PatientB   11
    PatientC   12
    PatientA   14
    PatientC   15
Each patient ID is hashed into a bin between 0 and 9
and printed in the last field:
    $ datamash --full strbin 1 < input.txt
    PatientA   10    5
    PatientB   11    6
    PatientC   12    7
    PatientA   14    5
    PatientC   15    7
Splitting the input into chunks can be done with awk:
    $ cat input.txt \
        | datamash --full strbin 1 \
        | awk '{print > $NF ".txt"}'

  Extracting numbers with getnum
The 'getnum' operation extracts a numeric value from the field:

    $ echo zoom-123.45xyz | datamash getnum 1
    123.45
getnum accepts an optional single-letter TYPE option:
    getnum:n - natural numbers (positive integers, including zero)
    getnum:i - integers
    getnum:d - decimal point numbers
    getnum:p - positive decimal point numbers (this is the default)
    getnum:h - hex numbers
    getnum:o - octal numbers

Examples:
    $ echo zoom-123.45xyz | datamash getnum 1
    123.45
    $ echo zoom-123.45xyz | datamash getnum:n 1
    123
    $ echo zoom-123.45xyz | datamash getnum:i 1
    -123
    $ echo zoom-123.45xyz | datamash getnum:d 1
    123.45
    $ echo zoom-123.45xyz | datamash getnum:p 1
    -123.45
    # Hex 0x123 = 291 Decimal
    $ echo zoom-123.45xyz | datamash getnum:h 1
    291
    # Octal 0123 = 83 Decimal
    $ echo zoom-123.45xyz | datamash getnum:o 1
    83

ADDITIONAL INFORMATION
See GNU Datamash Website (https://www.gnu.org/software/datamash)

ENVIRONMENT

LC_NUMERIC
    decimal-point character and thousands separator

AUTHOR
Written by Assaf Gordon, Tim Rice, Shawn Wagner, Erik Auerswald.

COPYRIGHT
Copyright © 2025 Assaf Gordon and Tim Rice License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
The full documentation for datamash is maintained as a Texinfo manual. If the info and datamash programs are properly installed at your site, the command

    info datamash

should give you access to the complete manual.