Fsdb::Filter::dbrowuniq(3)

NAME
dbrowuniq - eliminate adjacent rows with duplicate fields, maybe counting

SYNOPSIS
dbrowuniq [-cFLB] [uniquifying fields...]

DESCRIPTION
Eliminate adjacent rows with duplicate fields, perhaps counting them. Roughly equivalent to the Unix uniq command, but optionally only operating on the specified fields.

By default, all columns must be unique. If column names are specified, only those columns must be unique and the first row with those columns is returned.

Dbrowuniq eliminates only identical rows that adjacent. If you want to eliminate identical rows across the entirefile, you must make them adajcent, perhaps by using dbsort on your uniquifying field. (That is, the input with three lines a/b/a will produce three lines of output with both a's, but if you dbsort it, it will become a/a/b and dbrowuniq will output a/b.

By default, dbrowuniq outputs the first unique row. Optionally, with "-L", it will output the last unique row, or with "-B" it outputs both first and last. (This choice only matters when uniqueness is determined by specific fields.)

dbrowuniq can also count how many unique, adjacent lines it finds with "-c", with the count going to a new column (defaulting to "count"). Incremental counting, when the "count" column already exists, is possible with "-I". With incremental counting, the existing count column is summed.

OPTIONS

-c or --count
    Create a new column (count) which counts the number of times each line occurred.

    The new column is named by the "-N" argument, defaulting to "count".

-N on --new-name
    Specify the name of the count column, if any. (Default is "count".)

-I on --incremental
    Incremental counting. If the count column exists, it is assumed to have a partial count and the count accumulates. If the count column doesn't exist, it is created.

-L or --last
    Output the last unique row only. By default, it outputs the first unique row.

-F or --first
    Output the first unique row only. (This output is the default.)

-B or --both
    Output both the first and last unique rows.

This module also supports the standard fsdb options:

-d  Enable debugging output.

-i or --input InputSource
    Read from InputSource, typically a file name, or "-" for standard input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.

-o or --output OutputDestination
    Write to OutputDestination, typically a file name, or "-" for standard output, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.

--autorun or --noautorun
    By default, programs process automatically, but Fsdb::Filter objects in Perl do not run until you invoke the run() method. The "--(no)autorun" option controls that behavior within Perl.

--header H
    Use H as the full Fsdb header, rather than reading a header from then input.

--help
    Show help.

--man
    Show full manual.

SAMPLE USAGE

  Input:
    #fsdb      event
    _null_getpage+128
    _null_getpage+128
    _null_getpage+128
    _null_getpage+128
    _null_getpage+128
    _null_getpage+128
    _null_getpage+4
    _null_getpage+4
    _null_getpage+4
    _null_getpage+4
    _null_getpage+4
    _null_getpage+4
    #  | /home/johnh/BIN/DB/dbcol event
    #  | /home/johnh/BIN/DB/dbsort event

  Command:
    cat data.fsdb | dbrowuniq -c

  Output:
    #fsdb       event   count
    _null_getpage+128   6
    _null_getpage+4     6
    #   2       /home/johnh/BIN/DB/dbcol        event
    #  | /home/johnh/BIN/DB/dbrowuniq -c

SAMPLE USAGE 2
Retaining the last unique row as an example.

  Input:
        #fsdb event i
        _null_getpage+128 10
        _null_getpage+128 11
        _null_getpage+128 12
        _null_getpage+128 13
        _null_getpage+128 14
        _null_getpage+128 15
        _null_getpage+4 16
        _null_getpage+4 17
        _null_getpage+4 18
        _null_getpage+4 19
        _null_getpage+4 20
        _null_getpage+4 21
        #  | /home/johnh/BIN/DB/dbcol event
        #  | /home/johnh/BIN/DB/dbsort event

  Command:
    cat data.fsdb | dbrowuniq -c -L event

  Output:
        #fsdb event i count
        _null_getpage+128       15      6
        #  | /home/johnh/BIN/DB/dbcol event
        #  | /home/johnh/BIN/DB/dbsort event
        _null_getpage+4 21      6
        #   | dbrowuniq -c

SAMPLE USAGE 3
Incremental counting.

  Input:
    #fsdb       event   count
    _null_getpage+128   6
    _null_getpage+128   6
    _null_getpage+4     6
    _null_getpage+4     6
    #  /home/johnh/BIN/DB/dbcol event
    #  | /home/johnh/BIN/DB/dbrowuniq -c

  Command:
    cat data.fsdb | dbrowuniq -I -c event

  Output:
        #fsdb event count
        _null_getpage+128   12
        _null_getpage+4     12
        #  /home/johnh/BIN/DB/dbcol     event
        #  | /home/johnh/BIN/DB/dbrowuniq -c
        #   | dbrowuniq -I -c event

SEE ALSO
Fsdb.

CLASS FUNCTIONS

  new
    $filter = new Fsdb::Filter::dbrowuniq(@arguments);

Create a new dbrowuniq object, taking command-line arguments.

  set_defaults
    $filter->set_defaults();

Internal: set up defaults.

  parse_options
    $filter->parse_options(@ARGV);

Internal: parse command-line arguments.

  setup
    $filter->setup();

Internal: setup, parse headers.

  run
    $filter->run();

Internal: run over each rows.

AUTHOR and COPYRIGHT
Copyright (C) 1997-2018 by John Heidemann <johnh@isi.edu>

This program is distributed under terms of the GNU general public license, version 2. See the file COPYING with the distribution for details.