PHP: how to create associative array by key?

Question

I have simple array

array( 
   array( 'id'=>5, 'something' => 2, 'dsadsa' => 'fsfsd )
   array( 'id'=>20, 'something' => 2, 'dsadsa' => 'fsfsd )
   array( 'id'=>30, 'something' => 2, 'dsadsa' => 'fsfsd )
)

How to create associative array by id field (or something else) from it in the right way?

array( 
   '5' => array(  'something' => 2, 'dsadsa' => 'fsfsd )
   '20' => array(  'something' => 2, 'dsadsa' => 'fsfsd )
   '30' => array(  'something' => 2, 'dsadsa' => 'fsfsd )
)

Core Xii · Accepted Answer · 2012-07-16 08:03:25Z

2

Something along these lines.

$new_array = array();
foreach ($original_array as &$slice)
    {
    $id = (string) $slice['id'];
    unset($slice['id']);
    $new_array[$id] = $slice;
    }

answered Jul 16, 2012 at 8:03

Core Xii

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3 Comments

nkuhta Over a year ago

I can do it with foreach, but I thought, that PHP have some specials functions for that task...

Core Xii Over a year ago

It's a pretty specific task, I don't think there's a built-in function for it.

TerryE Over a year ago

This has a side effect of deleting the ['id'] elts from the original array, and because you don't unset $slice, any assignments to it will generate more side-effects in $new_array!

TerryE · Accepted Answer · 2012-07-16 09:28:01Z

@NikitaKuhta, nope. There is no slice function which returns a column of values in a 2D keyed table associated with a given key or column heading. You can use some of the callback array_... functions, but you will still need to execute a custom function per element so its just not worth it. I don't like Core Xii's solution as this corrupts the original array as a side effect. I suggest that you don't use references here:

$new_array = array();
foreach ($original_array as $slice) {
    $id = (string) $slice['id'];
    unset($slice['id']);
    $new_array[$id] = $slice;
}
# And now you don't need the missing unset( $slice)

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