CODEWITHSUNDEEP
phparrays
frumbert
frumbert

Reputation: 2427

custom array sort to force certain values to start or end of array

Say I have an array

$ar = ['apples','blueberries','end','pears','dragonfruit','oranges','start','durian','lychee','rambutan','pineapple','end','start'];

I want the array in some order (lets say alphabetic order for this argument), but with the values 'end' on the tail and 'start' on the head of the array.

function cmp($a,$b) {
    if ($a == $b) return 0;
    if ($b === 'start') return 1;
    if ($b === 'end') return -1;
    return ($a < $b) ? -1 : 1;
}

usort($ar,"cmp");

echo implode(", ", $ar);

How do I sort so that values matching a specific value will end up at the head or tail of the array, but other values will sort based on other criteria (e.g. numeric, alpha, etc)

Upvotes: 1

Views: 63

Answers (3)

Mukti Rani Ghosh
Mukti Rani Ghosh

Reputation: 577

Try this

$ar = ['apples','blueberries','end','pears','dragonfruit','oranges','start','durian','lychee','rambutan','pineapple','end','start', 'end', 'banana', 'yellow'];

function cmp($a, $b) {

    if ($a === $b) {
        return 0;
    }

    if ($a === 'start' ||  $b === 'end' ) {
        return -1;
    }

    if( $b === 'start' || $a === 'end') {
        return 1;
    }


    return ($a < $b) ? -1 : 1; }

    usort($ar,"cmp");

    echo implode(', ', $ar);

Hope this will help you

Upvotes: 1

Rakesh Jakhar
Rakesh Jakhar

Reputation: 6388

You can use array_diff with sort, array_push and array_unshift

 $elements = ['start','end'];//start & end elements array
 $rest     = array_diff($ar, $elements);
 sort($rest);//Sorting of the rest items
 array_push($rest, $elements[1]);//Push end element  
 array_unshift($rest, $elements[0]);//Push start element

You can use rsort($rest) for descending order.

Live Example : https://3v4l.org/GnotC

Upvotes: 1

ascsoftw
ascsoftw

Reputation: 3476

Following is how your cmp function should be. Just a couple of if statements introduced.

function cmp($a, $b) {

    if ($a === $b) {
        return 0;
    }

    if ($a === 'start' ) {
        return -1;
    }

    if( $b === 'start' ) {
        return 1;
    }

    if ($a === 'end' ) {
        return 1;
    }

    if ($b === 'end' ) {
        return -1;
    }     

    return ($a < $b) ? -1 : 1;
}

Upvotes: 0

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