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