[RESOLVED] Sorting multidimensional array by the sum of its subarrays

[phpSimon]

Hi everyone

I have an array:

Array
(
    [Name 1] => Array
        (
            [0] => 200
            [1] => 150
            [2] => 0
        )

[Name 2] => Array
    (
        [0] => 0
        [1] => 300
        [2] => 0
    )

[Name 3] => Array
    (
        [0] => 1000
        [1] => 1000
        [2] => 1000
    )

)

I need to sort the array by the sum of the subarray values; in the above case the new order would be:

Array
(
    [Name 3] => Array
        (
            [0] => 1000
            [1] => 1000
            [2] => 1000
        )

[Name 1] => Array
    (
        [0] => 200
        [1] => 150
        [2] => 0
    )

[Name 2] => Array
    (
        [0] => 0
        [1] => 300
        [2] => 0
    )

)

I've tried looking at usort but I can't work out how to use array_sum with it.

Can anyone help please?

Thank you

[phpSimon]

Halfway there !

// $resultarray is the input array

function sort_function(array $a, array $b) {
    $arr1_val = array_sum($a);
    $arr2_val = array_sum($b);
    return $arr2_val - $arr1_val;
}

usort($resultarray,sort_function);

print_r ($resultarray);

Array is now sorted with the largest sums at the top, but the keys have gone!

Anyone know what might be incorrect here?

Thanks again.

[phpSimon]

And... fixed by replacing usort with uasort.

I didn't know about uasort - I didn't even know about usort until today so a different version that maintains keys wasn't expected.

Any comments welcome though.