Adding duplicate array rows in Php

Question

I would like to create a function in PHP that adds together the rows of an array with a shared column value.

So input.

 $test = array(
    array("c", 5, 6),
    array("c", 2, 3),
    array("test", 5, 6)
 );

And output.

  $testduplicatefree = array(
    array("c", 7, 9),
    array("test", 5, 6)
    )
);

I'm thinking

function combine_duplicates($array,$col){
...
... 
return $duplicatefreearray; 
}

where the $col is the duplicate free array. So, in my case,

   combine_duplicates($test,0); 

would get me my desired output. Thanks for any help with this.

Answer 1

<?php

function combine_duplicates($array,$col) {
    $index = array();
    foreach ($array as $row) {
        $key = $row[$col];
        if (!isset($index[$key])) {
            $index[$key] = $row;
        } else {
            for ($i = 0; $i < count($row); ++$i) {
                if ($i != $col) {
                    $index[$key][$i] += $row[$i];
                }
            }
        }
    }

    return array_values($index);
}


$array = array(
    array("c", 5, 6),
    array("c", 2, 3),
    array("test", 5, 6)
);

print_r(combine_duplicates($array, 0));

Try it here: http://codepad.org/MDHEsqhi