CODEWITHSUNDEEP
phparraysmultidimensional-array
jamacoe
jamacoe

Reputation: 549

search or filter php array for a particular value and return outer index

I have defined a multi-dimensional array in php and I want to get the index of the 1st level, where a specific inner key has a certain value:

$arr = [
    [ [ "a" => "one",   "b" => "two", ],
      [ "a" => "three", "b" => "four", ],   
    ],
    [ [ "a" => "five",  "b" => "six", ],
      [ "a" => "seven", "b" => "eight", ],  
    ],
];

I want to get the index $i of the 1st level, where $arr[$i][$j]["b"] == "six".
Thus $arr[$i] should resolve to:

array(2) {
  [0]=>
  array(2) {
    ["a"]=>
    string(4) "five"
    ["b"]=>
    string(3) "six"
  }
  [1]=>
  array(2) {
    ["a"]=>
    string(5) "seven"
    ["b"]=>
    string(5) "eight"
  }
}

I could do this with a loop:

function getIndex($needle, $haystack) {
    for ($i = 0; $i < count($haystack); $i++) {
        for ($j = 0; $j < count($haystack[$i]); $j++) {
            if ( $haystack[$i][$j]['b'] == $needle ) {
                return $i;
            }
        }
    }
}

$x = $arr[ getIndex('six', $arr) ];
var_dump($x);

Can I achieve this without interation loops? With an expression to filter or search the array, like
$x = $arr[ <expression> ];

Upvotes: 0

Views: 150

Answers (1)

Nigel Ren
Nigel Ren

Reputation: 57131

A flexible way of trying to achieve this would be to pass a callback to the search function. This callback would be used to filter the data, only if there is a match will there be some data and this can be used to return the index where it matches.

So first a callback which would check the element of the array...

function check($haystack)
{
    return $haystack['b'] == 'six';
}

Then the function itself...

function getIndex(callable $filter, array $haystack)
{
    // Loop the base level of the array
    foreach ($haystack as $index => $subArray) {
        // If applying the filter method leaves some data, then it's found
        if (array_filter($subArray, $filter)) {
            return $index;
        }
    }

    // Return false for not found
    return false;
}

Then the actual usage

var_dump(getIndex('check', $arr));

Upvotes: 1

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