PHP how to remove key from multidimensional array?

Question

I want to remove key 1 from PHP array. I know how to achieve this by using foreach loop but i want array_filter solution. Anyone know How can I achieve this by using array filter method?

PHP Array:

Array (
    [0] => Array
        (
            [0] => 5000
            [1] => 25
            [2] => 44
        )

    [1] => Array
        (
            [0] => 5000
            [1] => 25
            [2] => 48
        )

    [2] => Array
        (
            [0] => 5000
            [1] => 26
            [2] => 44
        )

    [3] => Array
        (
            [0] => 5000
            [1] => 26
            [2] => 48
        )

)

Expected result:

Array
(
    [0] => Array
        (
            [0] => 5000
            [1] => 44
        )

    [1] => Array
        (
            [0] => 5000
            [1] => 48
        )

    [2] => Array
        (
            [0] => 5000
            [1] => 44
        )

    [3] => Array
        (
            [0] => 5000
            [1] => 48
        )

)

Mohammad · Accepted Answer · 2018-09-18 10:31:12Z

3

You can't use array_filter() for this purpose. Use array_reduce() instead

$newArr = array_reduce($array, function($carry, $item){
    $carry[] = [$item[0], $item[2]];
    return $carry;
});

Check result in demo

edited Sep 18, 2018 at 10:31

answered Sep 18, 2018 at 10:23

Mohammad

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Comments

Barmar · Accepted Answer · 2018-09-18 10:24:01Z

0

You can't use array_filter for this. array_filter processes the values, but you want to remove a specific key.

Use array_splice() to remove an index and have all following increments adjust.

foreach ($array as &$element) {
    array_splice($element, 1, 1);
}

The & makes this a reference variable, so modifying the variable affects the elements in the array.

answered Sep 18, 2018 at 10:24

Barmar

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2 Comments

mickmackusa Over a year ago

To be clear, array_filter() can be set to assess keys (though not the default behavior). Regardless, array_splice() is a better choice to reindex the subarrays.

Barmar Over a year ago

It can access keys, but since it preserves them in the result, it won't renumber the remaining elements. You would have to use $element = array_values($element); afterward to fix the indexes.

mickmackusa · Accepted Answer · 2021-02-14 13:24:22Z

If processing an array of indexed arrays, @Barmar's iterated array_splice() calls are ideal because they re-index the subarrays after the targeted key is removed. Here is a functional and dynamic variation on his answer.

(Both Demos)

$array = [
    [5000, 25, 44],
    [5000, 25, 48],
    [5000, 26, 44],
    [5000, 26, 48],
];

$omitKey = 1;

var_export(
    array_map(
        function($row) use($omitKey) {
            array_splice($row, $omitKey, 1);
            return $row;
        },
        $array
    )
);

If you have an array of associative arrays (not indexed), then array_splice() is not the correct tool because it relies on positions, not keys. Use unset() instead.

$array = [
    ['a' => 5000, 'b' => 25, 'c' => 44],
    ['a' => 5000, 'b' => 25, 'c' => 48],
    ['a' => 5000, 'b' => 26, 'c' => 44],
    ['a' => 5000, 'b' => 26, 'c' => 48],
];

$omitKey = 'b';

var_export(
    array_map(
        function($row) use($omitKey) {
            unset($row[$omitKey]);
            return $row;
        },
        $array
    )
);

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