Convert multidimensional array into single array

Question

I have an array which is multidimensional for no reason

/* This is how my array is currently */
Array
(
[0] => Array
    (
        [0] => Array
                


        

Answer 1

If you come across a multidimensional array that is pure data, like this one below, then you can use a single call to array_merge() to do the job via reflection:

$arrayMult = [ ['a','b'] , ['c', 'd'] ];
$arraySingle = call_user_func_array('array_merge', $arrayMult);
// $arraySingle is now = ['a','b', 'c', 'd'];

Answer 2

Recently I've been using AlienWebguy's array_flatten function but it gave me a problem that was very hard to find the cause of.
array_merge causes problems, and this isn't the first time that I've made problems with it either.
If you have the same array keys in one inner array that you do in another, then the later values will overwrite the previous ones in the merged array.

Here's a different version of array_flatten without using array_merge:

function array_flatten($array) { 
  if (!is_array($array)) { 
    return FALSE; 
  } 
  $result = array(); 
  foreach ($array as $key => $value) { 
    if (is_array($value)) { 
      $arrayList=array_flatten($value);
      foreach ($arrayList as $listItem) {
        $result[] = $listItem; 
      }
    } 
   else { 
    $result[$key] = $value; 
   } 
  } 
  return $result; 
} 

Answer 3

This single line would do that:

$array = array_column($array, 'plan');

The first argument is an array | The second argument is an array key.

For details, go to official documentation: https://www.php.net/manual/en/function.array-column.php.

Answer 4

Following this pattern

$input = array(10, 20, array(30, 40), array('key1' => '50', 'key2'=>array(60), 70));

Call the function :

echo "<pre>";print_r(flatten_array($input, $output=null));

Function Declaration :

function flatten_array($input, $output=null) {
if($input == null) return null;
if($output == null) $output = array();
foreach($input as $value) {
    if(is_array($value)) {
        $output = flatten_array($value, $output);
    } else {
        array_push($output, $value);
    }
}
return $output;

}

Answer 5

I've written a complement to the accepted answer. In case someone, like myself need a prefixed version of the keys, this can be helpful.

Array
(
    [root] => Array
        (
            [url] => http://localhost/misc/markia
        )

)

Array
(
    [root.url] => http://localhost/misc/markia
)

<?php
function flattenOptions($array, $old = '') {
  if (!is_array($array)) {
    return FALSE;
  }
  $result = array();
  foreach ($array as $key => $value) {
    if (is_array($value)) {
      $result = array_merge($result, flattenOptions($value, $key));
    }
    else {
      $result[$old . '.' . $key] = $value;
    }
  }
  return $result;
}

Answer 6

none of answers helped me, in case when I had several levels of nested arrays. the solution is almost same as @AlienWebguy already did, but with tiny difference.

function nestedToSingle(array $array)
{
    $singleDimArray = [];

    foreach ($array as $item) {

        if (is_array($item)) {
            $singleDimArray = array_merge($singleDimArray, nestedToSingle($item));

        } else {
            $singleDimArray[] = $item;
        }
    }

    return $singleDimArray;
}

test example

$array = [
        'first',
        'second',
        [
            'third',
            'fourth',
        ],
        'fifth',
        [
            'sixth',
            [
                'seventh',
                'eighth',
                [
                    'ninth',
                    [
                        [
                            'tenth'
                        ]
                    ]
                ],
                'eleventh'
            ]
        ],
        'twelfth'
    ];

    $array = nestedToSingle($array);
    print_r($array);

    //output
    array:12 [
        0 => "first"
        1 => "second"
        2 => "third"
        3 => "fourth"
        4 => "fifth"
        5 => "sixth"
        6 => "seventh"
        7 => "eighth"
        8 => "ninth"
        9 => "tenth"
        10 => "eleventh"
        11 => "twelfth"
   ]