Move array element by associative key to the beginning of an array - php

Question

So far all my research has shown that this cannot be achieved without writing lengthy functions such as the solution here
Surely there is a simpler way of achieving this using the predefined PHP functions?
Just to be clear, I am trying to do the following:
$test = array(
'bla' => 123,
'bla2' => 1234,
'bla3' => 12345
);
// Call some cool function here and return the array where the
// the element with key 'bla2' has been shifted to the beginning like so
print_r($test);
// Prints bla2=1234, bla=>123 etc...
I have looked at using the following functions but have so far have not been able to write a solution myself.
array_unshift
array_merge
To Summarize
I would like to:
Move an element to the beginning of an array
... whilst maintaining the associative array keys

Answer 1

This seems, funny, to me. But here ya go:
$test = array(
'bla' => 123,
'bla2' => 1234,
'bla3' => 12345
);
//store value of key we want to move
$tmp = $test['bla2'];
//now remove this from the original array
unset($test['bla2']);
//then create a new array with the requested index at the beginning
$new = array_merge(array('bla2' => $tmp), $test);
print_r($new);
Output looks like:
Array
(
[bla2] => 1234
[bla] => 123
[bla3] => 12345
)
You could turn this into a simple function that takes-in a key and an array, then outputs the newly sorted array.
UPDATE
I'm not sure why I didn't default to using uksort, but you can do this a bit cleaner:
$test = array(
'bla' => 123,
'bla2' => 1234,
'bla3' => 12345
);
//create a function to handle sorting by keys
function sortStuff($a, $b) {
if ($a === 'bla2') {
return -1;
}
return 1;
}
//sort by keys using user-defined function
uksort($test, 'sortStuff');
print_r($test);
This returns the same output as the code above.

Answer 2

This isn't strictly the answer to Ben's question (is that bad?) - but this is optimised for bringing a list of items to the top of the list.
/**
* Moves any values that exist in the crumb array to the top of values
* #param $values array of options with id as key
* #param $crumbs array of crumbs with id as key
* #return array
* #fixme - need to move to crumb Class
*/
public static function crumbsToTop($values, $crumbs) {
$top = array();
foreach ($crumbs AS $key => $crumb) {
if (isset($values[$key])) {
$top[$key] = $values[$key];
unset($values[$key]);
}
}
return $top + $values;
}