In Perl, how can I generate all possible combinations of a list?

Question

I have a file with a list, and a need to make a file that compares each line to the other. for example, my file has this:

AAA  
BBB  
CCC  
DDD  
EEE

I w

Answer 1

Use Algorithm::Combinatorics. The iterator based approach is preferable to generating everything at once.

#!/usr/bin/env perl

use strict; use warnings;
use Algorithm::Combinatorics qw(combinations);

my $strings = [qw(AAA BBB CCC DDD EEE)];

my $iter = combinations($strings, 2);

while (my $c = $iter->next) {
    print "@$c\n";
}

Output:

AAA BBB
AAA CCC
AAA DDD
AAA EEE
BBB CCC
BBB DDD
BBB EEE
CCC DDD
CCC EEE
DDD EEE