Group data from a 2d array by a column value and push the original row into its dedicated group

Question

I have this array

array
  0 => 
    array

      'prodid' => string '2' (length=1)
      'qty' => int 2
      'price' => string '100.00' (length=6)
      'sid' => string '13' (length=2)
  2 => 
    array

      'prodid' => string '3' (length=1)
      'qty' => int 1
      'price' => string '380.00' (length=6)
      'sid' => string '13' (length=2)
  1 => 
    array

      'prodid' => string '8' (length=1)
      'qty' => int 1
      'price' => string '300.00' (length=6)
      'sid' => string '24' (length=2)

How can i split it in to a multi dimentional array where the values 'sid' match like so.

array
  0 => 
    array

      0 => 
        array
          'prodid' => string '2' (length=1)
          'qty' => int 2
          'price' => string '100.00' (length=6)
          'sid' => string '13' (length=2)
      1 => 
        array
          'prodid' => string '2' (length=1)
          'qty' => int 2
          'price' => string '100.00' (length=6)
          'sid' => string '13' (length=2)

  1 => 
    array

      0 => 
        array
          'prodid' => string '7' (length=1)
          'qty' => int 1
          'price' => string '200.00' (length=6)
          'sid' => string '15' (length=2)

Answer 1

// $ouput array will be indexed by the 'sid' value
$output = array();

// Iterate over the main array and create a new subarray if 
// it doesn't already exist, or add to it if it does.
foreach($input as $subarr) {
  if (!isset($output[$subarr['sid']]) {
    // New array indexed by sid
    $output[$subarr['sid']] = array();
  }
  // Append the whole array
  $output[$subarr['sid']][] = $subarr;
}

Note: this produces slightly different output than you described, in that it uses the sid as array keys rather than just indexing them from 0:

array
  // Note key difference...
  // sid == 13
  13 => 
    array
      0 => 
        array
          'prodid' => string '2' (length=1)
          'qty' => int 2
          'price' => string '100.00' (length=6)
          'sid' => string '13' (length=2)
      1 => 
        array
          'prodid' => string '2' (length=1)
          'qty' => int 2
          'price' => string '100.00' (length=6)
          'sid' => string '13' (length=2)
  // sid == 15
  15 => 
    array

      0 => 
        array
          'prodid' => string '7' (length=1)
          'qty' => int 1
          'price' => string '200.00' (length=6)
          'sid' => string '15' (length=2)