Generate word combinations

Found from php.net shuffle doc

function powerSet($in,$minLength = 1) { 
   $count = count($in); 
   $members = pow(2,$count); 
   $return = array(); 
   for ($i = 0; $i < $members; $i++) { 
      $b = sprintf("%0".$count."b",$i); 
      $out = array(); 
      for ($j = 0; $j < $count; $j++) { 
         if ($b{$j} == '1') $out[] = $in[$j]; 
      }
      $out_val = implode(" ", $out); 
      if (count($out) >= $minLength) { 
         $return[] = $out_val; 
      } 
   } 
   return $return; 
}

print_r(powerSet($str_arr));

and the results will be,

Array
(
    [0] => windows
    [1] => microsoft
    [2] => microsoft windows
    [3] => new
    [4] => new windows
    [5] => new microsoft
    [6] => new microsoft windows
    [7] => buy
    [8] => buy windows
    [9] => buy microsoft
    [10] => buy microsoft windows
    [11] => buy new
    [12] => buy new windows
    [13] => buy new microsoft
    [14] => buy new microsoft windows
)

You can have a look at this PEAR PACKAGE Example usage:

<?php
require_once 'Math/Combinatorics.php';
$words = array('buy', 'new', 'microsoft');
$combinatorics = new Math_Combinatorics;
foreach($combinatorics->permutations($words, 2) as $p) {
  echo join(' ', $p), "\n"; 
}

The output will be:

buy new
new buy
buy microsoft
microsoft buy
new microsoft
microsoft new

function pc_permute($items, $perms = array( )) {
    if (empty($items)) {
        print join(' ', $perms) . "\n";
    } else {
        for ($i = count($items) - 1; $i >= 0; --$i) {
            $newitems = $items;
            $newperms = $perms;
            list($foo) = array_splice($newitems, $i, 1);
            array_unshift($newperms, $foo);
            pc_permute($newitems, $newperms);
        }
    }
}

source: http://docstore.mik.ua/orelly/webprog/pcook/ch04_26.htm#phpckbk-CHP-4-EX-6

also check next example on that site

---

example: pc_permute( explode( ' ', 'buy new microsoft windows' ) );

buy new microsoft windows
new buy microsoft windows
buy microsoft new windows
microsoft buy new windows
new microsoft buy windows
microsoft new buy windows
buy new windows microsoft
new buy windows microsoft
buy windows new microsoft
windows buy new microsoft
new windows buy microsoft
windows new buy microsoft
buy microsoft windows new
microsoft buy windows new
buy windows microsoft new
windows buy microsoft new
microsoft windows buy new
windows microsoft buy new
new microsoft windows buy
microsoft new windows buy
new windows microsoft buy
windows new microsoft buy
microsoft windows new buy
windows microsoft new buy

shuffle($array);
echo join(' ', array_slice($array, 0, mt_rand(1, count($array))));

This gives you one random "sentence". Repeat as necessary.