/ 
Fsdb-2.51
River stage zero No dependents
/ Fsdb::Filter::dbrowcount

NAME

dbrowcount - count the number of rows in an Fsdb stream

SYNOPSIS

dbrowcount

DESCRIPTION

Count the number of rows and write out a new fsdb file with one column (n) and one value: the number of rows. This program is a strict subset of dbcolstats.

Although there are other ways to get a count of rows (dbcolstats, or dbrowaccumulate -C 1 and some processing), counting is so common it warrents its own command. (For example, consider how often wc -l is used in regular shell scripting.) There are some gross and subtle differences, though, in thatd dbrowcount doesn't require one to specify a column to search, and it also doesn't look for and skip null data items.

OPTIONS

No program-specific options.

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.

--help

Show help.

--man

Show full manual.

SAMPLE USAGE

Input:

#fsdb      absdiff
0
0.046953
0.072074
0.075413
0.094088
0.096602
#  | /home/johnh/BIN/DB/dbrow 
#  | /home/johnh/BIN/DB/dbcol event clock
#  | dbrowdiff clock
#  | /home/johnh/BIN/DB/dbcol absdiff

Command:

cat data.fsdb | dbrowcount

Output:

#fsdb n
6
#  | /home/johnh/BIN/DB/dbrow 
#  | /home/johnh/BIN/DB/dbcol event clock
#  | dbrowdiff clock
#  | /home/johnh/BIN/DB/dbcol absdiff

Input 2:

As another example, this input produces the same output as above in dbrowcount, but different output in dbstats:

#fsdb      absdiff
-
-
-
-
-
-
#  | /home/johnh/BIN/DB/dbrow 
#  | /home/johnh/BIN/DB/dbcol event clock
#  | dbrowdiff clock
#  | /home/johnh/BIN/DB/dbcol absdiff

SEE ALSO

dbcolaccumulate(1), dbcolstats(1), Fsdb(3)

CLASS FUNCTIONS

new

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

set_defaults

$filter->set_defaults();

Internal: set up defaults.

parse_options

$filter->parse_options(@ARGV);

Internal: parse options

setup

$filter->setup();

Internal: setup, parse headers.

run

$filter->run();

Internal: run over all IO

finish

$filter->finish();

Internal: write trailer.

AUTHOR and COPYRIGHT

Copyright (C) 2007 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.