I don't know about the module, but its a fairly simple (recursive) subroutine:
use Data::Dumper;
my @a = (1..4);
my $len = 4;
print Dumper(combinations($len, @a));
sub combinations
{
my ($size, @elements) = @_;
return [] if $size < 1;
my @result = ();
foreach my $elem (@elements)
{
push @result,
map { [$elem, @$_] }
combinations($size-1,
grep { $_ != $elem }
@elements)
}
return @result;
}
--Dave
Update: for greater generality, replace foreach loop with
my @seen = ();
while (@elements)
{
my $elem = shift @elements;
push @result,
map { [$elem, @$_] }
combinations($size-1, @seen, @elements);
push @seen, $elem;
}
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