How to “flatten” a multi-dimensional array to simp

Question

It's probably beginner question but I'm going through documentation for longer time already and I can't find any solution. I thought I could use implode for each dimension and then put those strings back together with str_split to make new simple array. However I never know if the join pattern isn't also in values and so after doing str_split my original values could break.

Is there something like combine($array1, $array2) for arrays inside of multi-dimensional array?

Answer 1

In PHP>=5.3 and based on Luc M's answer (the first one) you can make use of closures like this

array_walk_recursive($aNonFlat, function(&$v, $k, &$t){$t->aFlat[] = $v;}, $objTmp);

I love this because I don't have to surround the function's code with quotes like when using create_function()

Answer 2

Using higher-order functions (note: I'm using inline anonymous functions, which appeared in PHP 5.3):

function array_flatten($array) {
    return array_reduce(
        $array,
        function($prev, $element) {
            if (!is_array($element))
                $prev[] = $element;
            else
                $prev = array_merge($prev, array_flatten($element));
            return $prev;
        },
        array()
    );
}

Answer 3

$array  = your array

$result = call_user_func_array('array_merge', $array);

echo "<pre>";
print_r($result);

REF: http://php.net/manual/en/function.call-user-func-array.php

Here is another solution (works with multi-dimensional array) :

function array_flatten($array) {

   $return = array();
   foreach ($array as $key => $value) {
       if (is_array($value)){ $return = array_merge($return, array_flatten($value));}
       else {$return[$key] = $value;}
   }
   return $return;

}

$array  = Your array

$result = array_flatten($array);

echo "<pre>";
print_r($result);

Answer 4

Given multi-dimensional array and converting it into one-dimensional, can be done by unsetting all values which are having arrays and saving them into first dimension, for example:

function _flatten_array($arr) {
  while ($arr) {
    list($key, $value) = each($arr); 
    is_array($value) ? $arr = $value : $out[$key] = $value;
    unset($arr[$key]);
  }
  return (array)$out;
}

Answer 5

// $array = your multidimensional array

$flat_array = array();

foreach(new RecursiveIteratorIterator(new RecursiveArrayIterator($array)) as $k=>$v){

$flat_array[$k] = $v;

}

Also documented: http://www.phpro.org/examples/Flatten-Array.html

Answer 6

A non-recursive solution (but order-destroying):

function flatten($ar) {
    $toflat = array($ar);
    $res = array();

    while (($r = array_shift($toflat)) !== NULL) {
        foreach ($r as $v) {
            if (is_array($v)) {
                $toflat[] = $v;
            } else {
                $res[] = $v;
            }
        }
    }

    return $res;
}