sum of duplicates in array php

Question

Im not sure what function to search for in regards to this so cant seem to help myself. Seems like an obvious problem really. I have an array, and where I have duplicate keys, I wish to add the values. e.g:

This is a section of my array.

[1] => Array
    (
        [inputAvg] => 21.41 KB
        [outputAvg] => 22.03 KB
        [date] => 2011-08-01
    )

[2] => Array
    (
        [inputAvg] => 182.63 KB
        [outputAvg] => 186.05 KB
        [date] => 2011-08-01
    )

[3] => Array
    (
        [inputAvg] => 182.63 KB
        [outputAvg] => 186.05 KB
        [date] => 2011-08-02
    )

[4] => Array
    (
        [inputAvg] => 4.84 MB
        [outputAvg] => 4.93 MB
        [date] => 2011-08-03
    )

All I wish to do is, say where the date key of the array is the same (e.g. here 2011-08-01) I want to show this date once, but with combined values of the duplicate item....?

e.g

[1] => Array
    (
        [inputAvg] => 204.04 KB
        [outputAvg] => 208.08 KB
        [date] => 2011-08-01
    )


[2] => Array
    (
        [inputAvg] => 182.63 KB
        [outputAvg] => 186.05 KB
        [date] => 2011-08-02
    )

[3] => Array
    (
        [inputAvg] => 4.84 MB
        [outputAvg] => 4.93 MB
        [date] => 2011-08-03
    )

Answer 1

<?php

$array  = array(Array("inputAvg" => 21.41,"outputAvg" => 22.03,"date" => "2011-08-01"),
                Array("inputAvg" => 182.63,"outputAvg" => 186.05,"date" => "2011-08-01" ),
                Array("inputAvg" => 182.63, "outputAvg" => 186.05,"date" => "2011-08-02")
                );

$res  = array();
foreach($array as $vals){
    if(array_key_exists($vals['date'],$res)){
        $res[$vals['date']]['inputAvg']    += $vals['inputAvg'];
        $res[$vals['date']]['outputAvg']   += $vals['outputAvg'];
        $res[$vals['date']]['date']        = $vals['date'];
    }
    else{
        $res[$vals['date']]  = $vals;
    }
}

echo "<pre>";
print_r($res);

?>

Output :

Array
(
    [2011-08-01] => Array
        (
            [inputAvg] => 204.04
            [outputAvg] => 208.08
            [date] => 2011-08-01
        )

    [2011-08-02] => Array
        (
            [inputAvg] => 182.63
            [outputAvg] => 186.05
            [date] => 2011-08-02
        )

)