PHP: remove element from multidimensional array (by key) using foreach

Question

I got multidimensional array. From each subarray, I would like to remove / unset values with index 1. My array $data.

Array
(
    [3463] => Array
        (
            [0] => 1
            [1] => 2014
            [context] => 'aaa'
        )

    [3563] => Array
        (
            [0] => 12
            [1] => 2014
            [context] => 'aaa'
        )       

    [2421] => Array
        (
            [0] => 5
            [1] => 2014
            [context] => 'zzz'
        )               
)

I would like to remove every element with index '1' from subarrays. Desired output is:

Array
(
    [3463] => Array
        (
            [0] => 1
            [context] => 'aaa'
        )

    [3563] => Array
        (
            [0] => 12
            [context] => 'aaa'
        )       

    [2421] => Array
        (
            [0] => 5
            [context] => 'zzz'
        )               
)

Why this does not work?

foreach ($data as $subArr) {
   foreach ($subArr as $key => $value) {
       if ($key == '1') {
        unset($subArr[$key]);
       }

   }
}

I'm sorry if this problem is trivial for you guys.

it is because foreach makes a copy of the element and does not work on the original array you can avoid this by assigning by reference. In order to be able to directly modify array elements within the loop precede $subArr with &. In that case the value will be assigned by reference. — Benjamin
– Benjamin, Commented Dec 15, 2014 at 11:26

Pang · Accepted Answer · 2017-05-02 03:24:33Z

17

easy way!? you can do this just with one foreach!

foreach ($data as $key => $subArr) {
    unset($subArr['1']);
    $data[$key] = $subArr;  
}

edited May 2, 2017 at 3:24

Pang

10.2k146 gold badges87 silver badges126 bronze badges

answered Dec 15, 2014 at 11:25

Pouya Darabi

2,30118 silver badges23 bronze badges

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1 Comment

Roemer Over a year ago

foreach ($data as $key => &$subArr) unset($subArr['1']);

Arun Kumar · Accepted Answer · 2014-12-15 11:24:38Z

11

you are making changes in subarray instead of main one try this may help

foreach ($data as $key => $subArr) { 
    unset($data[$key][1]);      
}

answered Dec 15, 2014 at 11:24

Arun Kumar

1,1988 silver badges15 bronze badges

Comments

axiac · Accepted Answer · 2014-12-15 11:31:37Z

It does not work because $subArr from the outer foreach contains copies of the values of $data and the inner foreach modifies these copies, leaving $data not touched.

You can fix that by telling PHP to make $subArr references to the original values stored in $data:

foreach ($data as &$subArr) {
   foreach ($subArr as $key => $value) {
       if ($key == '1') {
        unset($subArr[$key]);
       }
   }
}

Another option is to use function array_map(). It uses a callback function that can inspect (and modify) each value of $data and it returns a new array.

$clean = array_map(
    function (array $elem) {
        unset($elem['1']);        // modify $elem
        return $elem;             // and return it to be put into the result
    },
    $data
);

print_r($clean);

Suchit kumar · Accepted Answer · 2014-12-15 11:29:56Z

try this:

<?php 
    $data = Array
    (
        '3463' => Array
            (
                '0' => 1,
                '1' => 2014,
                'context' => 'aaa'
            ),

        '3563' => Array
            (
                '0' => 12,
                '1' => 2014,
                'context' => 'aaa'
            ),       

        '2421' => Array
            (
                '0' => 5,
                '1' => 2014,
                'context' => 'zzz'
            )               
    );

    foreach ($data as $k=>$subArr) {
        foreach ($subArr as $key => $value) {

            if ($key == '1') {
                unset($data[$k][$key]);
            }

        }
    }
print_r($data);// display the output

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