Simplify a nested array into a single level array [duplicate] - php

Question

This question already has answers here:
Closed 12 years ago.
Possible Duplicate:
How to Flatten a Multidimensional Array?
Let's say I have an array like this:
array (
1 =>
array (
2 =>
array (
16 =>
array (
18 =>
array (
),
),
17 =>
array (
),
),
),
14 =>
array (
15 =>
array (
),
),
)
How would I go about tranforming it into array like this?
array(1,2,16,18,17,14,15);

Answer 1

Sorry for the closevote. Didnt pay proper attention about you wanting the keys. Solution below:
$iterator = new RecursiveIteratorIterator(
new RecursiveArrayIterator($arr),
RecursiveIteratorIterator::SELF_FIRST);
$keys = array();
and then either
$keys = array();
foreach($iterator as $key => $val) {
$keys[] = $key;
}
or with the iterator instance directly
$keys = array();
for($iterator->rewind(); $iterator->valid(); $iterator->next()) {
$keys[] = $iterator->key();
}
or more complicated than necessary
iterator_apply($iterator, function(Iterator $iterator) use (&$keys) {
$keys[] = $iterator->key();
return TRUE;
}, array($iterator));
gives
Array
(
[0] => 1
[1] => 2
[2] => 16
[3] => 18
[4] => 17
[5] => 14
[6] => 15
)

Answer 2

how about some recursion
$result = array();
function walkthrough($arr){
$keys = array_keys($arr);
array_push($result, $keys);
foreach ($keys as $key)
{
if (is_array($arr[$key]))
walkthrough($arr[$key]);
else
array_push($result,$arr[$key]);
}
return $result;
}
walkthrouth($your_arr);
P.S.:Code can be bugged, but you've got an idea :)

Answer 3

function flattenArray($array) {
$arrayValues = array();
foreach (new RecursiveIteratorIterator( new RecursiveArrayIterator($array)) as $val) {
$arrayValues[] = $val;
}
return $arrayValues;
} // function flattenArrayIndexed()

Answer 4

If we consider the nested array as a tree structure, you can apply depth first traversal to convert it into a list. That is, into a single array you desire.

Answer 5

I have searched all similar questions and it seems there is no way without a recursion that would keep the keys order intact.
So I just went with classic recursion:
function getArrayKeysRecursive(array $theArray)
{
$aArrayKeys = array();
foreach ($theArray as $k=>$v) {
if (is_array($v)) {
$aArrayKeys = array_merge($aArrayKeys, array($k), getArrayKeysRecursive($v));
} else {
$aArrayKeys = array_merge($aArrayKeys, array($k));
}
}
return $aArrayKeys;
}