dbcoluniqcount - Man Page

dbrowuniq [-FLB] [uniquifying fields...]

Count number rows grouped by each value of field (or fields). Equivalent to the Fsdb dbrowuniq command with -c, but does not require the lines to be adjacent.

Unlike dbrowuniq, we do not require rows to be adajcent. By default we the number of unique rows is small and we cache them in memory, running quickly (O(n) time). Optionally in the future we will give up and fall back on external sorting, but this feature is not yet implemented.

As with dbroquniq, by default, dbcoluniqcount 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.)

Incremental counting, when the count column already exists, is possible with -I. With incremental counting, the existing count column is summed.

-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. Please specify the type with the name, if desired (allowing one to pick sizes smaller than the default quad, if desired). (Default is count:q.)

-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.

Retaining the last unique row as an example.

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

    cat data.fsdb | dbrowuniq -c -L event

        #fsdb event i count
        _null_getpage+128       15      6
        _null_getpage+4 21      6
        #  | /home/johnh/BIN/DB/dbcol event
        #  | /home/johnh/BIN/DB/dbsort event
        #   | dbcoluniqcount -L event

Fsdb, dbrowuniq.

Copyright (C) 1997-2025 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.