NAME
    App::CSVUtils - CLI utilities related to CSV

VERSION
    This document describes version 0.028 of App::CSVUtils (from Perl
    distribution App-CSVUtils), released on 2019-12-28.

DESCRIPTION
    This distribution contains the following CLI utilities:

    *   csv-add-field

    *   csv-avg

    *   csv-concat

    *   csv-convert-to-hash

    *   csv-delete-field

    *   csv-dump

    *   csv-each-row

    *   csv-grep

    *   csv-info

    *   csv-list-field-names

    *   csv-lookup-fields

    *   csv-map

    *   csv-munge-field

    *   csv-replace-newline

    *   csv-select-fields

    *   csv-select-row

    *   csv-setop

    *   csv-sort

    *   csv-sort-fields

    *   csv-sort-rows

    *   csv-split

    *   csv-sum

    *   csv2ltsv

    *   csv2tsv

    *   dump-csv

    *   tsv2csv

FUNCTIONS
  csv_add_field
    Usage:

     csv_add_field(%args) -> [status, msg, payload, meta]

    Add a field to CSV file.

    Your Perl code (-e) will be called for each row (excluding the header
    row) and should return the value for the new field. $main::row is
    available and contains the current row. $main::rownum contains the row
    number (2 means the first data row). $csv is the Text::CSV_XS object.
    $main::field_idxs is also available for additional information.

    Field by default will be added as the last field, unless you specify one
    of "--after" (to put after a certain field), "--before" (to put before a
    certain field), or "--at" (to put at specific position, 1 means as the
    first field).

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   after => *str*

        Put the new field after specified field.

    *   at => *int*

        Put the new field at specific position (1 means as first field).

    *   before => *str*

        Put the new field before specified field.

    *   eval* => *str|code*

        Perl code to do munging.

    *   field* => *str*

        Field name.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_avg
    Usage:

     csv_avg(%args) -> [status, msg, payload, meta]

    Output a summary row which are arithmetic averages of data rows.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    *   with_data_rows => *bool*

        Whether to also output data rows.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_concat
    Usage:

     csv_concat(%args) -> [status, msg, payload, meta]

    Concatenate several CSV files together, collecting all the fields.

    Example, concatenating this CSV:

     col1,col2
     1,2
     3,4

    and:

     col2,col4
     a,b
     c,d
     e,f

    and:

     col3
     X
     Y

    will result in:

     col1,col2,col4,col3
     1,2,
     3,4,
     ,a,b
     ,c,d
     ,e,f
     ,,,X
     ,,,Y

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filenames* => *array[filename]*

        Input CSV files.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_convert_to_hash
    Usage:

     csv_convert_to_hash(%args) -> [status, msg, payload, meta]

    Return a hash of field names as keys and first row as values.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   row_number => *int* (default: 2)

        Row number (e.g. 2 for first data row).

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_delete_field
    Usage:

     csv_delete_field(%args) -> [status, msg, payload, meta]

    Delete one or more fields from CSV file.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   fields* => *array[str]*

        Field names.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_dump
    Usage:

     csv_dump(%args) -> [status, msg, payload, meta]

    Dump CSV as data structure (array of array/hash).

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   hash => *bool*

        Provide row in $_ as hashref instead of arrayref.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_each_row
    Usage:

     csv_each_row(%args) -> [status, msg, payload, meta]

    Run Perl code for every row.

    Examples:

    *   Delete user data:

         csv_each_row(
             filename => "users.csv",
           eval => "unlink qq(/home/data/\$_->{username}.dat)",
           hash => 1
         );

    This is like csv_map, except result of code is not printed.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   eval* => *str|code*

        Perl code.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   hash => *bool*

        Provide row in $_ as hashref instead of arrayref.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_grep
    Usage:

     csv_grep(%args) -> [status, msg, payload, meta]

    Only output row(s) where Perl expression returns true.

    Examples:

    *   Only show rows where the amount field is divisible by 7:

         csv_grep( filename => "file.csv", eval => "\$_->{amount} % 7 ? 1:0", hash => 1);

    *   Only show rows where date is a Wednesday:

         csv_grep(
             filename => "file.csv",
           eval => "BEGIN { use DateTime::Format::Natural; \$parser = DateTime::Format::Natural->new } \$dt = \$parser->parse_datetime(\$_->{date}); \$dt->day_of_week == 3",
           hash => 1
         );

    This is like Perl's "grep" performed over rows of CSV. In $_, your Perl
    code will find the CSV row as an arrayref (or, if you specify "-H", as a
    hashref). $main::row is also set to the row (always as arrayref).
    $main::rownum contains the row number (2 means the first data row).
    $main::csv is the Text::CSV_XS object. $main::field_idxs is also
    available for additional information.

    Your code is then free to return true or false based on some criteria.
    Only rows where Perl expression returns true will be included in the
    result.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   eval* => *str|code*

        Perl code.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   hash => *bool*

        Provide row in $_ as hashref instead of arrayref.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_info
    Usage:

     csv_info(%args) -> [status, msg, payload, meta]

    Show information about CSV file (number of rows, fields, etc).

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_list_field_names
    Usage:

     csv_list_field_names(%args) -> [status, msg, payload, meta]

    List field names of CSV file.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_lookup_fields
    Usage:

     csv_lookup_fields(%args) -> [status, msg, payload, meta]

    Fill fields of a CSV file from another.

    Example input:

     # report.csv
     client_id,followup_staff,followup_note,client_email,client_phone
     101,Jerry,not renewing,
     299,Jerry,still thinking over,
     734,Elaine,renewing,
 
     # clients.csv
     id,name,email,phone
     101,Andy,andy@example.com,555-2983
     102,Bob,bob@acme.example.com,555-2523
     299,Cindy,cindy@example.com,555-7892
     400,Derek,derek@example.com,555-9018
     701,Edward,edward@example.com,555-5833
     734,Felipe,felipe@example.com,555-9067

    To fill up the "client_email" and "client_phone" fields of "report.csv"
    from "clients.csv", we can use: "--lookup-fields client_id:id
    --fill-fields client_email:email,client_phone:phone". The result will
    be:

     client_id,followup_staff,followup_note,client_email,client_phone
     101,Jerry,not renewing,andy@example.com,555-2983
     299,Jerry,still thinking over,cindy@example.com,555-7892
     734,Elaine,renewing,felipe@example.com,555-9067

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   count => *bool*

        Do not output rows, just report the number of rows filled.

    *   fill_fields* => *str*

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   ignore_case => *bool*

    *   lookup_fields* => *str*

    *   source* => *filename*

        CSV file to lookup values from.

    *   target* => *filename*

        CSV file to fill fields of.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_map
    Usage:

     csv_map(%args) -> [status, msg, payload, meta]

    Return result of Perl code for every row.

    Examples:

    *   Create SQL insert statements (escaping is left as an exercise for
        users):

         csv_map(
             filename => "file.csv",
           eval => "INSERT INTO mytable (id,amount) VALUES (\$_->{id}, \$_->{amount});",
           hash => 1
         );

    This is like Perl's "map" performed over rows of CSV. In $_, your Perl
    code will find the CSV row as an arrayref (or, if you specify "-H", as a
    hashref). $main::row is also set to the row (always as arrayref).
    $main::rownum contains the row number (2 means the first data row).
    $main::csv is the Text::CSV_XS object. $main::field_idxs is also
    available for additional information.

    Your code is then free to return a string based on some operation
    against these data. This utility will then print out the resulting
    string.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   add_newline => *bool* (default: 1)

        Whether to make sure each string ends with newline.

    *   eval* => *str|code*

        Perl code.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   hash => *bool*

        Provide row in $_ as hashref instead of arrayref.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_munge_field
    Usage:

     csv_munge_field(%args) -> [status, msg, payload, meta]

    Munge a field in every row of CSV file.

    Perl code (-e) will be called for each row (excluding the header row)
    and $_ will contain the value of the field, and the Perl code is
    expected to modify it. $main::row will contain the current row array.
    $main::rownum contains the row number (2 means the first data row).
    $main::csv is the Text::CSV_XS object. $main::field_idxs is also
    available for additional information.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   eval* => *str|code*

        Perl code to do munging.

    *   field* => *str*

        Field name.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_replace_newline
    Usage:

     csv_replace_newline(%args) -> [status, msg, payload, meta]

    Replace newlines in CSV values.

    Some CSV parsers or applications cannot handle multiline CSV values.
    This utility can be used to convert the newline to something else. There
    are a few choices: replace newline with space ("--with-space", the
    default), remove newline ("--with-nothing"), replace with encoded
    representation ("--with-backslash-n"), or with characters of your choice
    ("--with 'blah'").

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    *   with => *str* (default: " ")

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_select_fields
    Usage:

     csv_select_fields(%args) -> [status, msg, payload, meta]

    Only output selected field(s).

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   field_pat => *re*

        Field regex pattern to select.

    *   fields => *array[str]*

        Field names.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_select_row
    Usage:

     csv_select_row(%args) -> [status, msg, payload, meta]

    Only output specified row(s).

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   row_spec* => *str*

        Row number (e.g. 2 for first data row), range (2-7), or
        comma-separated list of such (2-7,10,20-23).

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_setop
    Usage:

     csv_setop(%args) -> [status, msg, payload, meta]

    Set operation against several CSV files.

    Example input:

     # file1.csv
     a,b,c
     1,2,3
     4,5,6
     7,8,9
 
     # file2.csv
     a,b,c
     1,2,3
     4,5,7
     7,8,9

    Output of intersection ("--intersect file1.csv file2.csv"), which will
    return common rows between the two files:

     a,b,c
     1,2,3
     7,8,9

    Output of union ("--union file1.csv file2.csv"), which will return all
    rows with duplicate removed:

     a,b,c
     1,2,3
     4,5,6
     4,5,7
     7,8,9

    Output of difference ("--diff file1.csv file2.csv"), which will return
    all rows in the first file but not in the second:

     a,b,c
     4,5,6

    Output of symmetric difference ("--symdiff file1.csv file2.csv"), which
    will return all rows in the first file not in the second, as well as
    rows in the second not in the first:

     a,b,c
     4,5,6
     4,5,7

    You can specify "--compare-fields" to only consider some fields only,
    for example "--union --compare-fields a,b file1.csv file2.csv":

     a,b,c
     1,2,3
     4,5,6
     7,8,9

    Each field specified in "--compare-fields" can be specified using
    "F1:F2:..." format to refer to different field names or indexes in each
    file, for example if "file3.csv" is:

     # file3.csv
     Ei,Si,Bi
     1,3,2
     4,7,5
     7,9,8

    Then "--union --compare-fields a:Ei,b:Bi file1.csv file3.csv" will
    result in:

     a,b,c
     1,2,3
     4,5,6
     7,8,9

    Finally you can print out certain fields using "--result-fields".

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   compare_fields => *str*

    *   filenames* => *array[filename]*

        Input CSV files.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   ignore_case => *bool*

    *   op* => *str*

        Set operation to perform.

    *   result_fields => *str*

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_sort_fields
    Usage:

     csv_sort_fields(%args) -> [status, msg, payload, meta]

    Sort CSV fields.

    This utility sorts the order of fields in the CSV. Example input CSV:

     b,c,a
     1,2,3
     4,5,6

    Example output CSV:

     a,b,c
     3,1,2
     6,4,5

    You can also reverse the sort order ("-r"), sort case-insensitively
    ("-i"), or provides the ordering, e.g. "--example a,c,b".

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   ci => *bool*

    *   example => *str*

        A comma-separated list of field names.

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   reverse => *bool*

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_sort_rows
    Usage:

     csv_sort_rows(%args) -> [status, msg, payload, meta]

    Sort CSV rows.

    This utility sorts the rows in the CSV. Example input CSV:

     name,age
     Andy,20
     Dennis,15
     Ben,30
     Jerry,30

    Example output CSV (using "--by-fields +age" which means by age
    numerically and ascending):

     name,age
     Dennis,15
     Andy,20
     Ben,30
     Jerry,30

    Example output CSV (using "--by-fields -age", which means by age
    numerically and descending):

     name,age
     Ben,30
     Jerry,30
     Andy,20
     Dennis,15

    Example output CSV (using "--by-fields name", which means by name
    ascibetically and ascending):

     name,age
     Andy,20
     Ben,30
     Dennis,15
     Jerry,30

    Example output CSV (using "--by-fields ~name", which means by name
    ascibetically and descending):

     name,age
     Jerry,30
     Dennis,15
     Ben,30
     Andy,20

    Example output CSV (using "--by-fields +age,~name"):

     name,age
     Dennis,15
     Andy,20
     Jerry,30
     Ben,30

    You can also reverse the sort order ("-r") or sort case-insensitively
    ("-i").

    For more flexibility, instead of "--by-fields" you can use "--by-code":

    Example output "--by-code '$a->[1] <=> $b->[1] || $b->[0] cmp $a->[0]'"
    (which is equivalent to "--by-fields +age,~name"):

     name,age
     Dennis,15
     Andy,20
     Jerry,30
     Ben,30

    If you use "--hash", your code will receive the rows to be compared as
    hashref, e.g. `--hash --by-code '$a->{age} <=> $b->{age} || $b->{name}
    cmp $a->{name}'.

    A third alternative is to sort using Sort::Sub routines. Example output
    (using "--by-sortsub 'by_length<r>' --key '$_->[0]'", which is to say to
    sort by descending length of name):

     name,age
     Dennis,15
     Jerry,30
     Andy,20
     Ben,30

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   by_code => *str|code*

        Sort using Perl code.

        $a and $b (or the first and second argument) will contain the two
        rows to be compared. Which are arrayrefs; or if "--hash" ("-H") is
        specified, hashrefs; or if "--key" is specified, whatever the code
        in "--key" returns.

    *   by_fields => *str*

        Sort by a comma-separated list of field specification.

        "+FIELD" to mean sort numerically ascending, "-FIELD" to sort
        numerically descending, "FIELD" to mean sort ascibetically
        ascending, "~FIELD" to mean sort ascibetically descending.

    *   by_sortsub => *str*

        Sort using a Sort::Sub routine.

        Usually combined with "--key" because most Sort::Sub routine expects
        a string to be compared against.

    *   ci => *bool*

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   hash => *bool*

        Provide row in $_ as hashref instead of arrayref.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   key => *str|code*

        Generate sort keys with this Perl code.

        If specified, then will compute sort keys using Perl code and sort
        using the keys. Relevant when sorting using "--by-code" or
        "--by-sortsub". If specified, then instead of rows the
        code/Sort::Sub routine will receive these sort keys to sort against.

        The code will receive the row as the argument.

    *   reverse => *bool*

    *   sortsub_args => *hash*

        Arguments to pass to Sort::Sub routine.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_split
    Usage:

     csv_split(%args) -> [status, msg, payload, meta]

    Split CSV file into several files.

    Will output split files xaa, xab, and so on. Each split file will
    contain a maximum of "lines" rows (options to limit split files' size
    based on number of characters and bytes will be added). Each split file
    will also contain CSV header.

    Warning: by default, existing split files xaa, xab, and so on will be
    overwritten.

    Interface is loosely based on the "split" Unix utility.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   lines => *uint* (default: 1000)

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

  csv_sum
    Usage:

     csv_sum(%args) -> [status, msg, payload, meta]

    Output a summary row which are arithmetic sums of data rows.

    This function is not exported.

    Arguments ('*' denotes required arguments):

    *   filename* => *filename*

        Input CSV file.

        Use "-" to read from stdin.

    *   header => *bool* (default: 1)

        Whether CSV has a header row.

        By default ("--header"), the first row of the CSV will be assumed to
        contain field names (and the second row contains the first data
        row). When you declare that CSV does not have header row
        ("--no-header"), the first row of the CSV is assumed to contain the
        first data row. Fields will be named "field1", "field2", and so on.

    *   tsv => *bool*

        Inform that input file is in TSV (tab-separated) format instead of
        CSV.

    *   with_data_rows => *bool*

        Whether to also output data rows.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

FAQ
  My CSV does not have a header?
    Use the "--no-header" option. Fields will be named "field1", "field2",
    and so on.

  My data is TSV, not CSV?
    Use the "--tsv" option.

  I have a big CSV and the utilities are too slow or eat too much RAM!
    These utilities are not (yet) optimized, patches welcome. If your CSV is
    very big, perhaps a C-based solution is what you need.

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/App-CSVUtils>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-App-CSVUtils>.

BUGS
    Please report any bugs or feature requests on the bugtracker website
    <https://rt.cpan.org/Public/Dist/Display.html?Name=App-CSVUtils>

    When submitting a bug or request, please include a test-file or a patch
    to an existing test-file that illustrates the bug or desired feature.

SEE ALSO
    App::TSVUtils

    App::LTSVUtils

    App::SerializeUtils

    setop.

    csv-select-row.

    csvgrep.

    csv-split.

AUTHOR
    perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2019, 2018, 2017, 2016 by
    perlancar@cpan.org.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

