http://www.perlmonks.org?node_id=250917


in reply to Creating tuples based on sets

You'll have to have multiple foreach loops that go through each item in the set. For tuples of size 2, you'll need two. For tuples of size 3, you'll need three. You get the idea. You might be able to use Algorithm::Loops to help you with this.

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Re^2: Creating tuples based on sets (nested loops)
by tye (Sage) on Apr 16, 2003 at 17:35 UTC

    Exactly what I was thinking. (:

    sub tuples { my( $count, @set )= @_; my @out; nestedLoops( [ ([0..$#set]) x $count ], { Code => sub { push @out, [@set[@_]] } } ); return \@out; } my $tuples= tuples( 2, qw(A B C) ); for my $tuple ( @$tuples ) { print "@$tuple\n"; }
    or, if you want to take advantage of iterators:
    sub tupleMaker { my( $count, @set )= @_; my $iter= nestedLoops( [ ([0..$#set]) x $count ] ); return sub { @set[ $iter->() ] }; } my $gen= tupleMaker( 2, qw(A B C) ); while( my @tuple= $gen->() ) { print "@tuple\n"; }
    which means you can deal with tons of tuples without needing tons of RAM.

                    - tye