perlman:perlfaq4 -> How do I permute N elements of a list?

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

It's been discussed before that Super Search is rather tough to find on the PM site, and I agree. Hence, there's your link.

Title edit by tye as Super Search should find only one match

It used to be really easy to find under Super Search, until somebody made another node with that name!

For n items there are 2^n combinations. Create a binary string for each combination number. Check each digit of the binary string to determine if the corresponding item gets printed.

YuckFoo

#!/usr/bin/perl

   use strict;

   my (@list) = qw(one two three four);

   printcombo(\@list);

#-----------------------------------------------------------
sub printcombo {

   my ($list) = @_;
   my (@print, $str, $i, $j);

   my $size = @{$list};

   for ($i = 0; $i < 2**$size; $i++) {
      $str = sprintf("%*.*b", $size, $size, $i);
      @print = ();
      for ($j = 0; $j < $size; $j++) {
         if (substr($str, $j, 1)) { push (@print, $list->[$j]); }
      }
      print join(' ', @print) . "\n";
   }
}
[download]

In the spirit of TIMTOWDI?

No.

That is the spirit of the lazy troll supporter ... providing solutions to FAQ questions easily found when so many have already answered them.

Teach them How to Read The Friendly Manual.

Sinners Repent!

Here is some code that works very well for me.

#! /usr/bin/perl -w

use strict;

my @array = @ARGV ? @ARGV : qw/mix up these words in new ways/;

sub fac {
   my $nr = shift;
   return 1 if $nr < 2;
   return $nr*fac($nr-1);
}

my %seen;
my $max = fac(scalar @array);
my $nr  = 0;
while( $nr < $max ) {
    my $need_combo = 1;
    my @combo;
    while( $need_combo ) {
        for( my $i = 0; $i < scalar @array; ++$i ) {
            $combo[$i] = $array[ rand scalar @array ];
        }
        my %unique;
        my $unique = 1;
        for my $c ( @combo ) {
            if( ++$unique{$c} > 1 ) {
                $unique = 0;
            }
        }
        if( $unique == 1 ) {
            $need_combo = 0;
        }
    }

    if( exists $seen{ "@combo" } ) {
        next;
    }
    else {
        local $" = "\t";
        print "@combo\n";
    }
    ++$seen{"@combo"};
    ++$nr;
}
[download]

There are possibly some minor performance tweaks that could be added, but I have chosen clarity over performance. Hope this helps.

Oops, I just re-read your question. You said you wanted combinations of this array, but apparently you also want selections. Oh well, I'm sure you can figure out easily enough how to extend this program to get it to do that too.