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PHP Exercises: Sort a collection of given arrays or objects by key

PHP: Exercise-93 with Solution

Write a PHP program to sort a collection of given arrays or objects by key.

Sample Solution: -

PHP Code:

<?php
//Licence: https://bit.ly/2CFA5XY

function orderBy($items, $attr, $order)
{
    $sortedItems = [];
    foreach ($items as $item) {
        $key = is_object($item) ? $item->{$attr} : $item[$attr];
        $sortedItems[$key] = $item;
    }
    if ($order === 'desc') {
        krsort($sortedItems);
    } else {
        ksort($sortedItems);
    }

    return array_values($sortedItems);
}
print_r(orderBy(
    [
        ['id' => 2, 'name' => 'Red'],
        ['id' => 3, 'name' => 'Black'],
        ['id' => 1, 'name' => 'Green']
    ],
    'id',
    'desc'
));
?>

Sample Output: 

Array
(
    [0] => Array
        (
            [id] => 3
            [name] => Black
        )

    [1] => Array
        (
            [id] => 2
            [name] => Red
        )

    [2] => Array
        (
            [id] => 1
            [name] => Green
        )

)

Flowchart:

Flowchart: Sort a collection of given arrays or objects by key.

PHP Code Editor:

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Previous: Write a PHP program to filter out the elements of an given array, that have one of the specified values.
Next: Write a PHP program to check if two numbers are approximately equal to each other.

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC