PHP 根据值列表对数组进行排序

Question

I'm looking for an approach to sort an array of arrays.

Here is simplified example;

$myArray = [ 
  ['ref' => 103, 'refList' => '101,102,111'],
  ['ref' => 104, 'refList' => '101,103'],
  ['ref' => 105, 'refList' => '106,103'],
  ['ref' => 106, 'refList' => '103,104,110'],
];

The sorting rule for the array items is;

Items with references contained in the 'refList' must come after any items with the matching 'ref'

So in this scenario the correct order would be;

  ['ref' => 103, 'refList' => '101,102,111'],
  ['ref' => 104, 'refList' => '101,103'],
  ['ref' => 106, 'refList' => '103,104'],
  ['ref' => 105, 'refList' => '106,103,110'],

I've tried some very long winded approaches and also usort(), but can't get this right. I went down the following route;

usort($myArray, 'refSorter');

function refSorter($a, $b) {

    $arrayOfRefs = explode(',', $b['refList']);

    if (in_array($a['ref'], $arrayOfRefs)) {
        return 1;
    }
    return 0;
}

Answer 1

You're missing one case in your comparison algorithm. You should return -1 when A ref is included in B refList and 1 when B ref is included in A refList.

$myArray = [ 
  ['ref' => 103, 'refList' => '101,102,111'],
  ['ref' => 104, 'refList' => '101,103'],
  ['ref' => 105, 'refList' => '106,103'],
  ['ref' => 106, 'refList' => '103,104,110'],
];

usort($myArray, 'refSorter');

function refSorter($a, $b) {
    $aRefs = explode(',', $a['refList']);
    $bRefs = explode(',', $b['refList']);

    if (in_array($a['ref'], $bRefs)) {
        return -1;
    }

    if (in_array($b['ref'], $aRefs)) {
        return 1;
    }

    return $a['ref'] <=> $b['ref'];
}

Result:

ref => 103 | refList => 101,102,111
ref => 104 | refList => 101,103
ref => 106 | refList => 103,104,110
ref => 105 | refList => 106,103

PHPSandbox

Answer 2

The sort rule is somewhat ambiguous, but how about this one (modify to match exact criteria):

function refSorter($a, $b) {

    $arrayOfRefsa = explode(',', $a['refList']);
    $arrayOfRefsb = explode(',', $b['refList']);

    $refCmp =  $a['ref'] === $b['ref'] ? 0 : ($a['ref'] < $b['ref'] ? -1 : 1);
    $refListCmp = in_array($b['ref'], $arrayOfRefsa) ? 1 : (in_array($a['ref'], $arrayOfRefsb) ? -1 : 0);
    return $refListCmp*10+$refCmp;
}

Gives correct output for example list given (tested)