Fsdb::Filter::dbrowuniq

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. 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.

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) 1997-2022 by John Heidemann <johnh AT isi DOT edu>

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