Advanced sorting of a multidimensional array in PHP

Question

I have looked through all the answers about sorting multidimensional arrays in PHP on Stack Overflow, but none have directly answered my question.

From the various answers I have understood that I should be using either the php usort function or the php array_multisort function, but I am not sure how to apply these to my very specific array structure:

Here is my variable $array:

Array
(
    [0] => Array
        (
            [field1] => 10
            [field2] => 100
            [field3] => 100
            [subarray] => Array
                (
                    [0] => Array
                        (
                            [field1] => 10
                            [field2] => 100
                            [field3] => 100
                        )

                    [1] => Array
                        (
                            [field1] => 10
                            [field2] => 100
                            [field3] => abcORDERBYTHIS
                        )

                )

        )

    [1] => Array
        (
            [field1] => 10
            [field2] => 100
            [field3] => 100
            [subarray] => Array
                (
                    [0] => Array
                        (
                            [field1] => 10
                            [field2] => 100
                            [field3] => 100
                        )

                    [1] => Array
                        (
                            [field1] => 10
                            [field2] => 100
                            [field3] => ghiORDERBYTHIS
                        )

                )

        )

    [2] => Array
        (
            [field1] => 10
            [field2] => 100
            [field3] => 100
            [subarray] => Array
                (
                    [0] => Array
                        (
                            [field1] => 10
                            [field2] => 100
                            [field3] => 100
                        )

                    [1] => Array
                        (
                            [field1] => 10
                            [field2] => 100
                            [field3] => defORDERBYTHIS
                        )

                )

        )

)

I would like to be able to sort this array by field3 of the last array in subarray. Accessing this element is easy enough with the php end function like so:

<?php
foreach($array as $array_single){
    foreach(end($array_single['subarray']) as $sub_array){
        echo $sub_array;
    }
}
?>

And from now on I'm stuck in how to specifically sort this multidimensional array alphabetically so that we get the following result:

$array[0] - Remains on top because the field3 value is abcORDERBYTHIS
$array[2] - Jumps into the middle because the field3 value is defORDERBYTHIS
$array[1] - Is now at the bottom because the field3 value is ghiORDERBYTHIS

Thanks in advance!

Sorry. While PHP over 100 array functions, there's no silver bullet. That's not to say a combination may not provide you what you want. — Jason McCreary
– Jason McCreary, Commented Feb 14, 2013 at 17:43

Fábio Hiroki · Accepted Answer · 2013-02-14 18:16:31Z

1

Try this code:

$array = Array();

$arraytemp['field1'] = 10;
$arraytemp['field2'] = 100;
$arraytemp['field3'] = 100;
$arraytemp['subarray'][0]["field1"] = 10;
$arraytemp['subarray'][0]["field2"] = 100;
$arraytemp['subarray'][0]["field3"] = 100;
$arraytemp['subarray'][1]["field1"] = 10;
$arraytemp['subarray'][1]["field2"] = 100;
$arraytemp['subarray'][1]["field3"] = "abcORDERBYTHIS";

$array[] = $arraytemp;

$arraytemp['field1'] = 10;
$arraytemp['field2'] = 100;
$arraytemp['field3'] = 100;
$arraytemp['subarray'][0]["field1"] = 10;
$arraytemp['subarray'][0]["field2"] = 100;
$arraytemp['subarray'][0]["field3"] = 100;
$arraytemp['subarray'][1]["field1"] = 10;
$arraytemp['subarray'][1]["field2"] = 100;
$arraytemp['subarray'][1]["field3"] = "ghiORDERBYTHIS";

$array[] = $arraytemp;

$arraytemp['field1'] = 10;
$arraytemp['field2'] = 100;
$arraytemp['field3'] = 100;
$arraytemp['subarray'][0]["field1"] = 10;
$arraytemp['subarray'][0]["field2"] = 100;
$arraytemp['subarray'][0]["field3"] = 100;
$arraytemp['subarray'][1]["field1"] = 10;
$arraytemp['subarray'][1]["field2"] = 100;
$arraytemp['subarray'][1]["field3"] = "defORDERBYTHIS";

$array[] = $arraytemp;

// Sort the multidimensional array
usort($array, "custom_sort");

// Define the custom sort function used in usort
function custom_sort($a,$b) {
    return strcmp($a['subarray'][1]["field3"], $b['subarray'][1]["field3"]);
}

answered Feb 14, 2013 at 18:16

Fábio Hiroki

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1 Comment

Jasdeep Khalsa Over a year ago

Thanks Fabio! This works perfectly as expected. I am marking this as the correct answer. Thanks for the quick response !!!

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