php array searching with keys

Question

Suppose an array like the following:

Array
(
    [a] => Array
        (
            [id] => 3
            [x] => binginb
        )

    [b] => Array
        (
            [id] => 5
            [x] => dibdab
        )

)

Now I would like to access this array based on its contents, so id and x in this case.

It would be nice here to be able to do something like

 $i = array_search(5,array_column($a,'id'));
 $stuff = dostuff($a[$i]['x']);

but that doesn't work since $a[1] is an undefined offset.

Is it possible to do anything like this without mutating the original array?

This might make sense for an id, but what would you expect back when there are multiple results? — jeroen
– jeroen, Commented Apr 24, 2018 at 19:25

Syscall · Accepted Answer · 2018-04-24 19:24:36Z

4

array_search() returns the index of the result of array_column(). You could use array_keys() to find the key for this index:

$a = [
   'a' => ['id' => 3, 'x' => 'binginb'],
   'b' => ['id' => 5, 'x' => 'dibdab'],
   ];
$i = array_search(5, array_column($a,'id'));
$key = array_keys($a)[$i]; // get the key at the $i index.
$stuff = dostuff($a[$key]['x']); // Here, $a[$key]['x'] = 'dibdab'

Note that array_search() could return FALSE if the value is not found. You could test the result (using a strict comparison) before to use it.

$i = array_search(5, array_column($a,'id'));
if ($i !== false) {
    $key = array_keys($a)[$i]; // get the key at the $i index.
    $stuff = dostuff($a[$key]['x']); // Here, $a[$key]['x'] = 'dibdab'
}

answered Apr 24, 2018 at 19:24

Syscall

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1 Comment

Mr. Hasquestions Over a year ago

And to extend the technique slightly, if you want to get all matches for something, ('id' == 5), you could do $k = array_keys... instead of array_search then print_r($a[array_keys($a)[$k[1]]]['x']); will be "'x' for the second element matching "ID = 5" in $a"

AbraCadaver · Accepted Answer · 2018-04-24 20:31:36Z

2

Use array_column to re-index the array by id:

$new = array_column($a, 'x', 'id');

Then to search for 5, just:

echo $new[5];

If you may have more than just x:

$new = array_column($a, null, 'id');

Then:

echo $new[5]['x'];

If you only do this once:

echo array_column($a, 'x', 'id')[5];

Or:

echo array_column($a, null, 'id')[5]['x'];

answered Apr 24, 2018 at 20:31

AbraCadaver

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Comments

MonkeyZeus · Accepted Answer · 2018-04-24 19:34:27Z

1

If you don't wish to be limited by PHP built-in functions then try this out:

<?php
function dostuff( $var1 )
{
    print_r($var1);
}

$a = [
   'a' => ['id' => 3, 'x' => 'binginb'],
   'b' => ['id' => 5, 'x' => 'dibdab'],
];

array_map( // 2: pass each element from the result from array_filter to dostuff()
    'dostuff',
    array_filter( // 1: filter $a based on the criteria defined in the anonymous function
        $a,
        function($item){
            return $item['id'] === 5;
        }
    )
);

Output:

Array
(
    [id] => 5
    [x] => dibdab
)

answered Apr 24, 2018 at 19:34

MonkeyZeus

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Comments

Anfath Hifans · Accepted Answer · 2018-04-24 20:09:20Z

0

i think it will help you,

<?php
$array = array(
    'a' => array(
        'id' => 3,
        'x' => 'binginb',
    ),
    'b' => array(
        'id' => 5,
        'x' => 'dibdab',
    )
);

$i = array_column($array,'x','id');

// Output of $i

Array ( [3] => binginb [5] => dibdab )

$stuff = dostuff($i[5]); // $i[5] return dibdab

answered Apr 24, 2018 at 20:09

Anfath Hifans

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