PHP Function to Reorder Array

Question

Is there a PHP function to move an array key/value pair and make it to become the first element in the array.

Basically, I will like to convert

Array
(
    [a] => rose
    [b] => tulip
    [c] => dahlia
    [d] => peony
    [e] => magnolia
)

to

Array
(
    [c] => dahlia
    [a] => rose
    [b] => tulip
    [d] => peony
    [e] => magnolia
)

To clarify, the aim is to pick one specific key/value pair and move it to become the first indexed while keeping the rest of the order intact.

So in this case, I am looking for something like

$old_array = Array
    (
        [a] => rose
        [b] => tulip
        [c] => dahlia
        [d] => peony
        [e] => magnolia
    );
$new_array = some_func($old_array, 'c');

In $new_array, 'c' should be first in the list.

Any ideas on code for 'some_func()'?

possible duplicate of Moving array element to top in PHP

FoamyGuy
– FoamyGuy

2012-07-10 01:50:00 +00:00
Commented Jul 10, 2012 at 1:50 — FoamyGuy
– FoamyGuy, Commented Jul 10, 2012 at 1:50

xdazz · Accepted Answer · 2012-07-07 15:47:23Z

2

If you only want to put one element to first, then you could do:

function some_func($array, $key) {
   $tmp = array($key => $array[$key]);
   unset($array[$key]);
   return $tmp + $array;
}

edited Jul 7, 2012 at 15:47

answered Jul 7, 2012 at 15:26

xdazz

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5 Comments

Dayo Over a year ago

At the risk of appearing to want to be fed everything, I don't have any sort logic apart from simply wanting to pass a key and have that key (plus associated value) move to the first index position. Can you help with that?

xdazz Over a year ago

@Dayo I wrote the some_func for your requirement :)

Matthew Over a year ago

PHP's sort algorithm is not stable, so using it isn't very trivial for this case. You'd have to index every element before sorting so that you could preserve order. A non-sort answer is likely to be the most efficient.

Mahesh Meniya Over a year ago

You should check for key If key is not exist then it will add key at first position but value will be not available.

Dayo Over a year ago

@xdazz Thanks for the modified version. It is similar to Mahesh's answer which I accepted as it came earlier.

Mahesh Meniya · Accepted Answer · 2012-07-07 15:39:36Z

1

This may helpful to you :

function myfun($ar,$key){
    if (array_key_exists($key,$ar)) {
        $arr_tmp = array($key => $ar[$key]);
        unset($ar[$key]);
        return $arr_tmp + $ar;        
    }
}

answered Jul 7, 2012 at 15:39

Mahesh Meniya

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Comments

ohaal · Accepted Answer · 2012-07-07 15:55:38Z

1

function some_func($arr, $key) {
    $val = $arr[$key];
    unset($arr[$key]);
    return array_merge(array($key => $val), $arr);
}

See it on codepad

answered Jul 7, 2012 at 15:55

ohaal

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