PHP - RecursiveArrayIterator recurse on all but last level

Question

I need to flatten a multidimensional array, but not flattening the last level.

For example, consider the following array

$array = [
    1 => [
        1 => [
            'anna',
            'alice'
        ],
        2 => [
            'bob',
            'bartold'
        ]
    ],
    2 => [
        1 => [
            'carol'
        ],
        2 => [
            'david'
        ]
    ]
];

The following code

$result = [];

$iterator = new \RecursiveIteratorIterator(
    new \RecursiveArrayIterator($array)
);

foreach ($iterator as $row) {
    $result[] = $row;
}

returns the following array

array(6) {
  [0]=>
  string(4) "anna"
  [1]=>
  string(5) "alice"
  [2]=>
  string(3) "bob"
  [3]=>
  string(7) "bartold"
  [4]=>
  string(5) "carol"
  [5]=>
  string(5) "david"
}

What I would like to obtain is the following:

[
    1 => [
        'anna',
        'alice'
    ],
    2 => [
        'bob',
        'bartold'
    ],
    3 => [
        'carol'
    ],
    4 => [
        'david'
    ]
];

not flattening the last level of the array. Is there an easy way to obtain this?

Possibly I would like to use iterators.

If you want you could try to play with this.

did you try with array_walk_recursive? php.net/manual/en/function.array-walk-recursive.php — briosheje
– briosheje, Commented Apr 15, 2015 at 15:16
@briosheje yes, I tried, the result is exactly the same as the one that I get with the code I posted — marcosh
– marcosh, Commented Apr 15, 2015 at 15:17
You can't get what you want for two reasons: 1) The nesting logic of the node [1] is different from node [2]. 2) you're somehow assigning new keys that cannot be logically recreated in a recursive loop (keys 1,2,3,4 in the output), because it is recursive. I would personally suggest you to either perform a nested foreach loop or to just implement an ad-hoc function. — briosheje
– briosheje, Commented Apr 15, 2015 at 15:54

tmt · Accepted Answer · 2015-04-16 09:21:54Z

2

You can flatten the array recursively while on each element you would look ahead if it contains subarrays and change merging based on it:

<?php

function flattenArrayWithLookAhead($include = array()) {
  $new = array();

  foreach($include as $item) {
    if(is_array($item)) {
      $containsArrays = array_reduce($item, function ($carry, $current) {
        if(is_array($current) || $carry === true) return true;
        else return false;
      });

      if($containsArrays) $new = array_merge($new, flattenArrayWithLookAhead($item));
      else $new[] = $item;
    } else {
      $new[] = $item;
    }
  }

  return $new;
}

$array = flattenArrayWithLookAhead($array);

online TEST

(NOTE: I'm sure the function can be simplified but my love for recursive functions is currently at its minimum.)

edited Apr 16, 2015 at 9:21

answered Apr 15, 2015 at 16:03

tmt

8,7544 gold badges35 silver badges49 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Machavity · Accepted Answer · 2015-04-15 15:43:36Z

1

Remember that recursive iterators always walk the data structure to return the data nodes, not the preceding structure. To keep the structure as well you could do a nested foreach

$newdata = array();
foreach($data as $group) {
    foreach($group as $set) {
        $newdata[] = $set;
    }
}

answered Apr 15, 2015 at 15:43

Machavity♦

31.8k27 gold badges97 silver badges108 bronze badges

1 Comment

marcosh Over a year ago

the problem with the nested foreach is that if I need to add a nesting level near the root, my code would not work anymore. I guess that the only solution would be to use a recursive function

Collectives™ on Stack Overflow

PHP - RecursiveArrayIterator recurse on all but last level

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related