Question

How do I multiply the values of a multi-dimensional array with weights and sum up the results into a new array in PHP or in general?

The boring way looks like this:

$weights = array(0.25, 0.4, 0.2, 0.15); $values  = array            (               array(5,10,15),               array(20,25,30),               array(35,40,45),               array(50,55,60)            ); $result  = array();  for($i = 0; $i < count($values[0]); ++$i) {   $result[$i] = 0;   foreach($weights as $index => $thisWeight)     $result[$i] += $thisWeight * $values[$index][$i]; } 

Is there a more elegant solution?

Answer 1

Depends on what you mean by elegant, of course.

function weigh(&$vals, $key, $weights) {     $sum = 0;     foreach($vals as $v)         $sum += $v*$weights[$key];     $vals = $sum; }  $result = $values; array_walk($result, 'weigh', $weights); 

EDIT: Sorry for not reading your example better. I make result a copy of values, since array_walk works by reference.