Set multi-dimensional array by key path from array values?

Question

Sorry for the terrible title, best I could think of at the time! Say I have a 'path' array like so;

array('this', 'is', 'the', 'path')

What would be the most effective method to end up with the array below?

array(
    'this' => array(
        'is' => array(
            'the' => array(
                'path' => array()
            )
        )
    )
)

Answer 1

Just iterate over it with something like array_shift or array_pop:

$inarray = array('this', 'is', 'the', 'path',);
$tree = array();
while (count($inarray)) {
    $tree = array(array_pop($inarray) => $tree,);
}

Not tested, but that's the basic structure of it. Recursion also fits the task well. Alternatively, if you don't want to modify the initial array:

$inarray = array('this', 'is', 'the', 'path',);
$result = array();
foreach (array_reverse($inarray) as $key)
    $result = array($key => $result,);

Answer 2

I use two similar functions to get and set values by their path within an array:

function array_get($arr, $path)
{
    if (!$path)
        return null;

    $segments = is_array($path) ? $path : explode('/', $path);
    $cur =& $arr;
    foreach ($segments as $segment) {
        if (!isset($cur[$segment]))
            return null;

        $cur = $cur[$segment];
    }

    return $cur;
}

function array_set(&$arr, $path, $value)
{
    if (!$path)
        return null;

    $segments = is_array($path) ? $path : explode('/', $path);
    $cur =& $arr;
    foreach ($segments as $segment) {
        if (!isset($cur[$segment]))
            $cur[$segment] = array();
        $cur =& $cur[$segment];
    }
    $cur = $value;
}

Then you use them like this:

$value = array_get($arr, 'this/is/the/path');
$value = array_get($arr, array('this', 'is', 'the', 'path'));
array_set($arr, 'here/is/another/path', 23);

Answer 3

function buildArrayFromPath( $path ) {
  $out = array();
  while( $pop = array_pop($path) ) $out = array($pop => $out);
  return $out;
}

Answer 4

One recursive solution:

function find_in_array(&$array, &$path, $_i=0) {
  // sanity check
  if ( !(is_array($array) && is_array($path)) ) return false;
  $c = count($path); if ($_i >= $c) return false;

  $k = $path[$_i];
  if (array_key_exists($k, $array))
    return ($_i == $c-1) ? $array[$k] : find_in_array($array[$k], $path, $_i+1);
  else
    return false;
}

Parameter $_i is for internal use and should not be set when calling the function.

Answer 5

not really elegant. but it works

$start = array('this', 'is', 'the', 'path')

$result[ $start[0] ][ $start[1] ][ $start[2] ][ $start[3] ] = array ();