Sort an Array by keys based on another Array?

Question

Is it possible in PHP to do something like this? How would you go about writing a function? Here is an example. The order is the most important thing.

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Answer 1

PHP has functions to help you with this:

$arrayToBeSorted = array('west', 'east', 'south', 'north');
$order = array('north', 'south', 'east', 'west');

// sort array
usort($arrayToBeSorted, function($a, $b) use ($order){
    // sort using the numeric index of the second array
    $valA = array_search($a, $order);
    $valB = array_search($b, $order);

    // move items that don't match to end
    if ($valA === false)
        return -1;
    if ($valB === false)
        return 0;

    if ($valA > $valB)
        return 1;
    if ($valA < $valB)
        return -1;
    return 0;
});

Usort does all the work for you and array_search provides the keys. array_search() returns false when it can't find a match so items that are not in the sort array naturally move to the bottom of the array.

Note: uasort() will order the array without affecting the key => value relationships.