Re: counting pairwise incidences

When you count strings, think of a hash.

I'm not sure if I understood what pairs you want counted. If a line has the entries a, b, c, d, do you want the pairs ab, ac, ad, bc, bd, cd?

If yes, this code should do what you want:

use strict;
use warnings;

my %pairs;
while (<DATA>) {
    my @names = split;
    for my $first (0..$#names - 1) {
        for my $second ($first + 1 .. $#names) {
            my $p = join '_', @names[$first, $second];
            $pairs{$p}++;
        }
    }
}
while (my ($k, $v) = each %pairs) {
    print "$k: $v\n";
}

__DATA__
tomD gly4 phil
aesG tomD gly4 phil
aesG phil
aesG tomD gly4
[download]

If not, you need to explain what pairs you want to count.

Perl 6 - second systems done right

Comment on Re: counting pairwise incidences Download Code

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Re^2: counting pairwise incidences by ikegami (Patriarch) on May 17, 2011 at 17:26 UTC
Looks like ab ac ad to me, in which case it simplifies to: `use strict; use warnings; my %pairs; while (<DATA>) { my ($first, @names) = split; for my $second (@names) { my $p = join '_', $first, $second; ++$pairs{$p}; } } while (my ($k, $v) = each %pairs) { print "$k: $v\n"; } __DATA__ tomD gly4 phil aesG tomD gly4 phil aesG phil aesG tomD gly4` [download]	[reply] [d/l]
Re^2: counting pairwise incidences by LanX (Saint) on May 17, 2011 at 14:52 UTC
IMHO you should sort @names. apart from this it's practically the same algorith I use. :) Cheers Rolf	[reply]