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

arrays, combinations, combinatorics, perl

Solution

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

Problem

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 would like the final list to look like this: ``` AAA BBB AAA CCC AAA DDD AAA EEE BBB CCC BBB DDD BBB EEE CCC DDD CCC EEE DDD EEE ``` I am trying to do this in Perl, for this first time and am having a little trouble. I do know that you need to make an array, and then split it, but after that I am having some trouble.

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