Question

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Sorting multidimensional array in PHP

How can I sort by key in a multidimensional array?

For instance, below is the array I print from my db, where the latest comes first – December, November, October, etc and 2011, 2010, 2009, etc

Array
(
    [0] => Array
        (
            [URL] => september 2011
            [Title] => September 2011
            [Date] => 8
            [Month] => 9
            [Year] => 2011
        )

    [1] => Array
        (
            [URL] => january 2011
            [Title] => January 2011
            [Date] => 1
            [Month] => 2
            [Year] => 2011
        )

    [2] => Array
        (
            [URL] => february 2011
            [Title] => February 2011
            [Date] => 4
            [Month] => 1
            [Year] => 2011
        )

    [3] => Array
        (
            [URL] => november 2011
            [Title] => November 2011
            [Date] => 23
            [Month] => 11
            [Year] => 2010
        )

    [4] => Array
        (
            [URL] => april 2011
            [Title] => April 2011
            [Date] => 23
            [Month] => 4
            [Year] => 2010
        )

)

But I need it to be like this, October, November, December, etc and 2011, 2010, 2009, etc – note the months are sorted by the oldest comes first but the years are still sorted by the latest comes first.

So the array should be sorted like this,

Array
(

    [2] => Array
        (
            [URL] => february 2011
            [Title] => February 2011
            [Date] => 4
            [Month] => 1
            [Year] => 2011
        )

    [1] => Array
        (
            [URL] => january 2011
            [Title] => January 2011
            [Date] => 1
            [Month] => 2
            [Year] => 2011
        )

    [0] => Array
        (
            [URL] => september 2011
            [Title] => September 2011
            [Date] => 8
            [Month] => 9
            [Year] => 2011
        )

    [4] => Array
        (
            [URL] => april 2010
            [Title] => April 2010
            [Date] => 23
            [Month] => 4
            [Year] => 2010
        )

    [3] => Array
        (
            [URL] => november 2010
            [Title] => November 2010
            [Date] => 23
            [Month] => 11
            [Year] => 2010
        )
)

Is that possible?

Answer 1

Generic solution to sort arrays of arrays with multiple keys

Based on my answer to this question, here is a very generic solution that you can use in lots of situations.

Limitation: Requires PHP >= 5.3 to work, due to the presence of anonymous functions.

New and improved, now with descending sort support

function make_comparer() {
    $criteriaNames = func_get_args();
    $comparer = function($first, $second) use ($criteriaNames) {
        // Do we have anything to compare?
        while(!empty($criteriaNames)) {
            // What will we compare now?
            $criterion = array_shift($criteriaNames);

            // Used to reverse the sort order by multiplying
            // 1 = ascending, -1 = descending
            $sortOrder = 1; 
            if (is_array($criterion)) {
                $sortOrder = $criterion[1] == SORT_DESC ? -1 : 1;
                $criterion = $criterion[0];
            }

            // Do the actual comparison
            if ($first[$criterion] < $second[$criterion]) {
                return -1 * $sortOrder;
            }
            else if ($first[$criterion] > $second[$criterion]) {
                return 1 * $sortOrder;
            }

        }

        // Nothing more to compare with, so $first == $second
        return 0;
    };

    return $comparer;
}

How to use it

To sort by year ascending:

uasort($array, make_comparer('Year'));

To sort by year ascending, then by month ascending:

uasort($array, make_comparer('Year', 'Month'));

To sort by year descending, then by month ascending:

uasort($array, make_comparer(array('Year', SORT_DESC), 'Month'));

This last one is what you ‘re after.