in reply to Faster alternative to Math::Combinatorics

Hi AppleFritter,

further to my previous post (http://www.perlmonks.org/?node_id=1198575), this is another version of my program which seem to produce results more in line with what you seem to be expecting (assuming I have understood what you're expecting). Or, at least, the number of output lines seems to be what you're looking for.

use strict; use warnings; my @list = (0, 2, 3); for my $w (1, 2, 3, 4, 7, 8) { print "count = $w\n"; make_sets2($w, "", @list); } sub make_sets2 { my $weight = shift; my $temp_result = shift; print "$temp_result\n" and return if $weight <= 0; while (@_) { my $item = shift; make_sets2( $weight -1, "$temp_result$item, ", ($item, @_)); } }
Now, the (abbreviated) result looks like this:
$ time perl multisets.pl count = 1 0, 2, 3, count = 2 0, 0, 0, 2, 0, 3, 2, 2, 2, 3, 3, 3, count = 3 0, 0, 0, 0, 0, 2, 0, 0, 3, 0, 2, 2, 0, 2, 3, 0, 3, 3, 2, 2, 2, 2, 2, 3, 2, 3, 3, 3, 3, 3, count = 4 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 2, 2, 0, 0, 2, 3, 0, 0, 3, 3, 0, 2, 2, 2, 0, 2, 2, 3, 0, 2, 3, 3, 0, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, count = 7 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 2, 2, . . . (abbreviated) 2, 2, 2, 3, 3, 3, 3, 3, 2, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, real 0m0.048s user 0m0.015s sys 0m0.000s
Since the output is much smaller, redirecting the output does not make a very significant performance difference:
$ time perl multisets.pl > /dev/null real 0m0.043s user 0m0.000s sys 0m0.031s
But, frankly, I still do not understand why you seem to be looking for a subset of all the possible combinations.