php string to array structure

Question

In php, I need to turn this array:

array(
 'group1_selector1_rule1' => value
, 'group1_selector1_rule2' => value
, 'group1_selector1_rule3' => value
, 'group1_selector2_rule1' => value
, 'group1_selector2_rule2' => value
, 'group2_selector1_rule1' => value
, 'group2_selector1_rule2' => value
, 'group3_selector1_rule1' => value
, 'group3_selector2_rule1' => value
, 'group3_selector2_rule2' => value
);

into this:

array(
 'group1' => array(
 'selector1' => array(
 'rule1' => value
 , 'rule2' => value
 , 'rule3' => value
 )
 , 'selector2' => array(
 'rule1' => value
 , 'rule2' => value
 )
 ) // end group 1
, 'group2' => array(
 'selector1' => array(
 'rule1' => value
 , 'rule2' => value
 )
 ) // end group 2
, 'group3' => array(
 'selector1' => array(
 'rule1' => value
 )
 , 'selector2' => array(
 'rule1' => value
 , 'rule2' => value
 )
 ) // end group 3
); // end array

If anyone out there would like to suggest a smart way, I'd be interested :) I think I could labour some algorithm, but I'd like something elegant and have a feeling that some clever use of explode() and some 'array_merging' functions could do it?

Answer 1

 $res_array = array();
 foreach ($array as $key=>$value) {
 $x = explode("_", $key);
 $res_array[$x[0]][$x[1]][$x[2]] = $value;
 }
 var_dump($res_array);

for $array

$array = array(
 'group1_selector1_rule1' => 'value1'
, 'group1_selector1_rule2' => 'value2'
, 'group1_selector1_rule3' => 'value3'
, 'group1_selector2_rule1' => 'value4'
, 'group1_selector2_rule2' => 'value5'
, 'group2_selector1_rule1' => 'value6'
, 'group2_selector1_rule2' => 'value7'
, 'group3_selector1_rule1' => 'value8'
, 'group3_selector2_rule1' => 'value9'
, 'group3_selector2_rule2' => 'value10'
);

Output:

array(3) {
 ["group1"]=>
 array(2) {
 ["selector1"]=>
 array(3) {
 ["rule1"]=>
 string(6) "value1"
 ["rule2"]=>
 string(6) "value2"
 ["rule3"]=>
 string(6) "value3"
 }
 ["selector2"]=>
 array(2) {
 ["rule1"]=>
 string(6) "value4"
 ["rule2"]=>
 string(6) "value5"
 }
 }
 ["group2"]=>
 array(1) {
 ["selector1"]=>
 array(2) {
 ["rule1"]=>
 string(6) "value6"
 ["rule2"]=>
 string(6) "value7"
 }
 }
 ["group3"]=>
 array(2) {
 ["selector1"]=>
 array(1) {
 ["rule1"]=>
 string(6) "value8"
 }
 ["selector2"]=>
 array(2) {
 ["rule1"]=>
 string(6) "value9"
 ["rule2"]=>
 string(7) "value10"
 }
 }
}

• mikkelbreum: that was fast :) thanks a lot, saved me half an evening here!

Answer 2

<?
$poo=array(
 'group1_selector1_rule1' => 'value'
, 'group1_selector1_rule2' => 'value'
, 'group1_selector1_rule3' => 'value'
, 'group1_selector2_rule1' => 'value'
, 'group1_selector2_rule2' => 'value'
, 'group2_selector1_rule1' => 'value'
, 'group2_selector1_rule2' => 'value'
, 'group3_selector1_rule1' => 'value'
, 'group3_selector2_rule1' => 'value'
, 'group3_selector2_rule2' => 'value'
);
foreach ($poo as $k=>$v){
 list($a,$b,$c) = explode('_',$k);
 $new[$a][$b][$c]=$v;
}
print_r($new);

http://www.ideone.com/skv0a

• mikkelbreum: thanks, and great tool you showed me ideone.com I like that it shows memory usage and execution time, makes it possible to compare solutions. sorry I can't accept both answers. this one seems slightly more elegant from the syntax, but I guess they do roughly the same.

Answer 3

How about a generic solution?

<?php
function transform($oldArray)
{
 $newArray = array();
 foreach ($oldArray as $selector => $value)
 {
 $parts = explode('_', $selector);
 $last = array_pop($parts);
 $arr = &$newArray;
 foreach ($parts as $part)
 {
 if (!is_array($arr[$part])) $arr[$part] = array();
 $arr = &$arr[$part];
 }
 $arr[$last] = $value;
 }
 return $newArray;
}
?>

• mikkelbreum: thanks, good point regarding the generic vs. specific solutions.