PHP Array Restructuration - php

Question

I have pairs of keys identified by their respective ID like this:
array(
'key_a_0' => $a,
'key_a_1' => $a,
'key_b_0' => $b,
'key_b_1' => $b
)
I need this structure:
array(
'0' => array(
'key_a' => $a,
'key_b' => $b
),
'1' => array(
'key_a' => $a,
'key_b' => $b
)
)
What would be the best way to achieve this?

Answer 1

Provided this is exactly how all the data is present as, and stays as, this would then be simple to amend into the format you require with a simple foreach loop.
$new = array();
foreach($data as $key => $variable){
list($name,$var,$index) = explode("_", $key);
$new[$index][$name . '_' . $var] = $variable;
}
This returns;
Array
(
[0] => Array
(
[key_a] => 5
[key_b] => 10
)
[1] => Array
(
[key_a] => 5
[key_b] => 10
)
)
Example
Ideally - you'd want to set your array structure at creation, as Dagon said.

Answer 2

The following should do the job. This assumes, however, that the initial array comes in a specific order and that order is what is expected within each nested array in the final array, and that the keys in the initial array are always in that format.
$a = 5;
$b = 10;
$aRawArray = array(
'key_a_0' => $a,
'key_a_1' => $a,
'key_b_0' => $b,
'key_b_1' => $b,
);
$aFormattedArray = array();
foreach ($aRawArray as $sKey => $mValue) {
$aKeyParts = explode('_', $sKey);
$sExtractedKey = $aKeyParts[2];
$sNewKey = $aKeyParts[0] . '_' . $aKeyParts[1];
if (!isset($aFormattedArray[$sExtractedKey])) {
$aFormattedArray[$sExtractedKey] = array();
}
$aFormattedArray[$sExtractedKey][$sNewKey] = $mValue;
}
var_dump($aFormattedArray);