PHP: calculate array values by array <p>This may be simple to some of you guys but I'm really dummy in php. All what I need is just to transform a multidimensional array and calculate some of it's sub array values.</p> <pre><code> Array ( [0] =&gt; Array ( [date] =&gt; 2014-10-30 [mission] =&gt; one [point] =&gt; 10 ) [1] =&gt; Array ( [date] =&gt; 2014-10-31 [mission] =&gt; five [point] =&gt; 10 ) [2] =&gt; Array ( [date] =&gt; 2014-11-19 [mission] =&gt; one [point] =&gt; 8 ) </code></pre> <p>And the output would be like:</p> <pre><code> Array ( [one] =&gt; Array ( [mission] =&gt; one [point] =&gt; 18 // sum all points where [mission] =&gt; one [count] =&gt; 2 [everage] =&gt; 9 // 18/2 ) [five] =&gt; Array ( [mission] =&gt; five [point] =&gt; 10 [count] =&gt; 1 [everage] =&gt; 10 ) </code></pre> <p>It is simple to get the sum of <code>[point]</code> values using <code>foreach</code> but troubles begin when I try to get <code>count</code> of arrays with same <code>[mission]</code> value. Thats my code:</p> <pre><code>foreach($missionsarray as $row) { if(!isset($newarray[ $row['mission'] ])) { $newarray[ $row['mission'] ] = $row; $newarray[ $row['mission'] ]['count'] = count($row['point']); continue ; } $newarray[ $row['mission'] ]['point'] += $row['point']; } print_r($newarray); </code></pre>