Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi, Not sure how to go about this, say i have file1 with 
aa
aa
aa
ff
ff
dd

[download]
i need to have an additional number column next to this, but the numbers only increment when the row in column one changes. 
aa 1
aa 1
aa 1
ff 2
ff 2
dd 3

[download]
numbering is not dependent on letter in column 1, just alters when change. Thanks

Replies are listed 'Best First'.
Re: incrementing a column
by Limbic~Region (Chancellor) on Sep 28, 2004 at 14:13 UTC
    Anonymous Monk,
    Since you were not overly verbose on your requirements, this is the best I can offer: 
    #!/usr/bin/perl
use strict;
use warnings;

my $prev_col;
my $counter;
while ( <DATA> ) {
    chomp;
    my ($col, $rest) = $_ =~ /^([^\s]+)(\s.*)$/;
    if ( ! defined $prev_col || $col ne $prev_col ) {
        $counter++;
        $prev_col = $col;
    }
    print "$col $counter$rest\n";
}
__DATA__
aa one two three
aa four five six
xy z
xy a
xy b
cc asdfasdf

    [download]

    Cheers - L~R

[reply]
[d/l]
Re: incrementing a column
by ikegami (Patriarch) on Sep 28, 2004 at 14:10 UTC 
    my $last;
my $i = 0;
while (<IN>) {
   chomp;
   $i++ if (!defined($last) || $_ ne $last);
   $last = $_;
   print OUT ("$_ $i\n");
}

    [download]

    One liner:

    perl -lpe "$i++ if ($_ ne $last); $last = $_; $_.=' '.$i;" inputfile >
+ outputfile

    [download]

    (Swap ' for " and vice-versa if you're not using Windows.)

    Update: eek, that's what I get for not testing. Added the missing $last=$_.

[reply]
[d/l]
[select]

      In your one liner ITYM if( $_ ne $last ) { $i++; $last = $_ }.

[reply]
[d/l]
Re: incrementing a column
by Anonymous Monk on Sep 28, 2004 at 14:28 UTC 
    perl -i.bak -pe '$_[$#_]eq$_ or$_[@_]=$_;$_.=" ".@_'

    [download]
[reply]
[d/l]
A reply falls below the community's threshold of quality. You may see it by logging in.

Back to Seekers of Perl Wisdom