Permutation of Array PHP

Question

I have the following problem:

$multidmimensional = array(

 [0] => array(
    [0] => 1, 
    [1] => 2, 
    [2] => 3
  );


  [1] => array(
   [0] => 5, 
   [1] => 6, 
   [2] => 7
  );

  ...

  [2] => array(
   [0] =>,4 
   [1] => 5, 
  );

);

I can have one or more (nested) arrays, and lets take as an example the first two of the above arrays:

I should permutate them in the following way:

If I had for example those three arrays, I should get a result like this:

I am having some problems to make an algorithm that would fix this problem. Can anyone help me? Thanks in advance.

Can we see the code you have thus far? Also, if you would format your code with indentation and <pre> tags, that would make it easier to read. — halfer
– halfer, Commented May 24, 2012 at 9:17
Please, learn to Markdown. No need for tons of <br> and unreadable code. — deceze
– deceze ♦, Commented May 24, 2012 at 9:20

Paul · Accepted Answer · 2012-05-24 10:17:13Z

That's a nice brain teasing question. Here's what I came up with, see the running demo for testing and adjusting.

$multidimensional = array(
  0 => array(
    0 => 1,
    1 => 2,
    2 => 3,
  ),
  1 => array(
    0 => 5,
    1 => 6,
    2 => 7,
  ),
  2 => array(
    0 => 4,
    1 => 5,
  ),
); // just your input


$permutations = array();
$count = count($multidimensional);
for ($i = 0; $i < $count; $i++) {
  $temp = array_map("permute",array($permutations),array($multidimensional[$i]));
  $permutations = $temp[0];
}
print_r($permutations); // OUTPUT

function permute($base,$add) {
  $result = array();
  if (count($base) > 0) {
    foreach ($base AS $val1) {
      if (count($add) > 0) {
        foreach ($add AS $val2) {
          $result[] = $val1.$val2;
        }
      }
      else {
        $result = $base;
      }
    }
  }
  else {
    $result = $add;
  }
  return $result;
}

Oliver A. · Accepted Answer · 2012-05-24 11:39:07Z

0

I can not test it right now but this should work: (may contain typos)

function permute($arrays){
      if(count($arrays)<2) return $arrays[0];//TODO error on count == 0
      $array1 = array_shift($arrays);
      $array2 = array_shift($arrays);
      $results = array();
      foreach($array1 as $elementOfOne){
        foreach($array2 as $elementOfTwo){
          $results[] = $elemnetOfOne . $elementOfTwo;
        }
      }
      array_unshift($arrays, $results);
      return permute($arrays);
    }

answered May 24, 2012 at 11:39

Oliver A.

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Comments

Diptendu · Accepted Answer · 2014-12-26 14:14:11Z

0

$data = array
(
  '1' => array(5, 6, 7),
  '2' => array(9, 25, 14)

);

for($i=0; $i<=count(array_keys($data)); $i++) {
   for($j=1; $j<=2; $j++) {
      $values[$i][] = $data[$j][$i];
   }
}

for($i=0; $i<count($values); $i++) {
  shuffle($values[$i]);
}

$newData = array();
for($i=0; $i<3; $i++) {
   for($j=1; $j<=2; $j++) {
       $newData[$j][] = array_pop($values[$i]);
   }
}
print_r($newData);

Fiddle

answered Dec 26, 2014 at 14:14

Diptendu

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1 Comment

Tom Over a year ago

this works only for the array exactly as given, so much as changing the index will break it.

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