#!/usr/bin/perl

#
# dbrowdiff.pm
# Copyright (C) 1991-2024 by John Heidemann <johnh@isi.edu>
#
# This program is distributed under terms of the GNU general
# public license, version 2.  See the file COPYING
# in $dblibdir for details.
#


=head1 NAME

dbrowdiff - compute row-by-row differences of some column

=head1 SYNOPSIS

dbrowdiff [-B|-I|-F] [-A AbsDiffColumnName] [-P PctDiffColumnName] column

=head1 DESCRIPTION

For a given column, compute the differences between each row
of the table.  Differences are output to two new columns,
C<absdiff> and C<pctdiff>.

Differences are either relative to the previous column 
(I<incremental> mode), or relative to the first row
(I<baseline> mode), the default.
Alternatively, in I<future> mode, differences
are between the I<next> row and the current row.

If column names are given, with C<-A> or C<-P>,
then only columns with that name are produced.


=head1 OPTIONS

=over 4

=item B<-B> or B<--baseline>

Select baseline mode (the default), where differences are relative to the first row.

=item B<-I> or B<--incremental>

Select incremental mode, where differences are relative to the previous row.

=item B<-F> or B<--future>

Select future  incremental mode, where differences are
incremental between the next row and the current one.

=item B<-A> COL or B<--absdiff> COL

Name the absolute difference output column COL,
and don't output percent difference unless C<-P> is given.

=item B<-P> COL or B<--pctdiff> COL

Name the percent difference output column COL,
and don't output absolute difference unless C<-P> is given.

=item B<-f FORMAT> or B<--format FORMAT>

Specify a L<printf(3)>-style format for output statistics.
Defaults to C<%.5g>.

=item B<-e> EmptyValue or B<--empty>

Specify the value for the last row when in future mode.

=back


=for comment
begin_standard_fsdb_options

This module also supports the standard fsdb options:

=over 4

=item B<-d>

Enable debugging output.

=item B<-i> or B<--input> InputSource

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

=item B<-o> or B<--output> OutputDestination

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

=item B<--autorun> or B<--noautorun>

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

=item B<--help>

Show help.

=item B<--man>

Show full manual.

=back

=for comment
end_standard_fsdb_options


=head1 SAMPLE USAGE

=head2 Input:

    #fsdb      event   clock:d
    _null_getpage+128       815812813.281756
    _null_getpage+128       815812813.328709
    _null_getpage+128       815812813.353830
    _null_getpage+128       815812813.357169
    _null_getpage+128       815812813.375844
    _null_getpage+128       815812813.378358
    #  | /home/johnh/BIN/DB/dbrow 
    #  | /home/johnh/BIN/DB/dbcol event clock

=head2 Command:

    cat DATA/kitrace.fsdb | dbrowdiff clock

=head2 Output:

    #fsdb      event   clock:d   absdiff:d pctdiff:d
    _null_getpage+128       815812813.281756        0       0
    _null_getpage+128       815812813.328709        0.046953        5.7554e-09
    _null_getpage+128       815812813.353830        0.072074        8.8346e-09
    _null_getpage+128       815812813.357169        0.075413        9.2439e-09
    _null_getpage+128       815812813.375844        0.094088        1.1533e-08
    _null_getpage+128       815812813.378358        0.096602        1.1841e-08
    #  | /home/johnh/BIN/DB/dbrow 
    #  | /home/johnh/BIN/DB/dbcol event clock
    #  | dbrowdiff clock


=head1 SEE ALSO

L<Fsdb>.
L<dbcolmovingstats>.
L<dbrowuniq>.
L<dbfilediff>.

L<dbrowdiff>, L<dbrowuniq>, and L<dbfilediff> are similar but different.
L<dbrowdiff> computes row-by-row differences for a column,
L<dbrowuniq> eliminates rows that have no differences,
and L<dbfilediff> compares fields of two files.


=cut


# WARNING: This code is derived from dbrowdiff.pm; that is the master copy.

use Fsdb::Filter::dbrowdiff;
my $f = new Fsdb::Filter::dbrowdiff(@ARGV);
$f->setup_run_finish;  # or could just --autorun
exit 0;


=head1 AUTHOR and COPYRIGHT

Copyright (C) 1991-2024 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.

=cut

1;