CODEWITHSUNDEEP
php
user1493356
user1493356

Reputation:

PHP: Move associative array element to beginning of array

What would be the best method of moving any element of an associative array to the beginning of the array?

For example, say I have the following array:

$myArray = array(
    'two'   => 'Blah Blah Blah 2',
    'three' => 'Blah Blah Blah 3',
    'one'   => 'Blah Blah Blah 1',
    'four'  => 'Blah Blah Blah 4',
    'five'  => 'Blah Blah Blah 5',
);

What i want to do is move the 'one' element to the beginning and end up with the following array:

$myArray = array(
    'one'   => 'Blah Blah Blah 1',
    'two'   => 'Blah Blah Blah 2',
    'three' => 'Blah Blah Blah 3',
    'four'  => 'Blah Blah Blah 4',
    'five'  => 'Blah Blah Blah 5',
);

Upvotes: 108

Views: 51279

Answers (6)

Mark Eirich
Mark Eirich

Reputation: 10114

You can use the array union operator (+) to join the original array to a new associative array using the known key (one).

$myArray = array('one' => $myArray['one']) + $myArray;
// or      ['one' => $myArray['one']] + $myArray;

Array keys are unique, so it would be impossible for it to exist in two locations.

See further at the doc on Array Operators:

The + operator returns the right-hand array appended to the left-hand array; for keys that exist in both arrays, the elements from the left-hand array will be used, and the matching elements from the right-hand array will be ignored.

Upvotes: 210

Eugene Kaurov
Eugene Kaurov

Reputation: 2991

if you have 2 arrays, 1st has elements to move to the top of 2nd array of elements, you can use

$result = \array_replace($ArrayToMoveToTop, $myArray);

Here is a code sample:

//source array    
$myArray = [
    'two' => 'Blah Blah Blah 2',
    'three' => 'Blah Blah Blah 3',
    'one' => 'Blah Blah Blah 1',
    'four' => 'Blah Blah Blah 4',
    'five' => 'Blah Blah Blah 5',
];
// set necessary order
$orderArray = [
    'one' => '',
    'two' => '',
];
//apply it
$result = \array_replace($orderArray, $myArray);
\print_r($result);

Upvotes: 1

You Old Fool
You Old Fool

Reputation: 22941

Here's another simple one-liner that gets this done using array_splice():

$myArray = array_splice($myArray,array_search('one',array_keys($myArray)),1) + $myArray;

Upvotes: 2

Sune
Sune

Reputation: 677

A bit late, but in case anyone needs it, I created this little snippet.

function arr_push_pos($key, $value, $pos, $arr) 
{
    $new_arr = array();
    $i = 1;

    foreach ($arr as $arr_key => $arr_value) 
    {
        if($i == $pos) 
            $new_arr[$key] = $value;

        $new_arr[$arr_key] = $arr_value;

        ++$i;
    }

    return $new_arr;
}

Just adjust it to suit your needs, or use it and unset the index to move. Works with associative arrays too.

Upvotes: 2

trante
trante

Reputation: 34006

If you have numerical array keys and want to reindex array keys, it would be better to put it into array_merge like this:

$myArray = array_merge(array($key => $value) + $myArray );

Upvotes: 7

Emil Vikström
Emil Vikström

Reputation: 91942

There's a function in the comments of the PHP manual for array_unshift which can be used to add an element, with key, to the beginning of an array:

function array_unshift_assoc(&$arr, $key, $val)
{
    $arr = array_reverse($arr, true);
    $arr[$key] = $val;
    return array_reverse($arr, true);
}

Unset the element and reinsert it again with the above function:

$tmp = $myArray['one'];
unset($myArray['one']);
$myArray = array_unshift_assoc($myArray, 'one', $tmp);

A more general approach may be to use uksort to sort your array by keys and provide a sorting function of your own.

Upvotes: -2

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