Create a flat array of values from an array column containing array-type data

Question

I have this array in PHP.

$all = array(
array(
    'titulo' => 'Nome 1',
    'itens' => array( 'item1', 'item2', 'item3')
),
array(
    'titulo' => 'Nome 2',
    'itens' => array( 'item4', 'item5', 'item6')
),
array(
    'titulo' => 'Nome 4',
    'itens' => array( 'item7', 'item8', 'item9')
));

I need to merge specific child arrays. In other words, I need to get the itens column of data (which contains array-type data) as a flat result array like this:

$filteredArray = array('item1', 'item2', 'item3', 'item4', 'item5', 'item6', 'item7', 'item8', 'item9');

I can do this using foreach(), but are there any other more elegant methods?

Possible duplicate of [I want to add sub arrays to one single array in php](https://stackoverflow.com/questions/14951811/i-want-to-add-sub-arrays-to-one-single-array-in-php) — ishegg, Sep 25 '17 at 19:15
@ishegg that duplicate is not appropriate for this question because the OP doesn't want to flatten the entire contents of the input array, just one column of data. This is an important distinction. — mickmackusa, Apr 08 '21 at 02:52

Don't Panic · Accepted Answer · 2017-09-25T19:50:57.413

3

You can reduce the itens column of your array, using array_merge as the callback.

$filteredArray = array_reduce(array_column($all, 'itens'), 'array_merge', []);

Or even better, eliminate the array_reduce by using the "splat" operator to unpack the column directly into array_merge.

$result = array_merge(...array_column($all, 'itens'));

edited Sep 25 '17 at 19:50

answered Sep 25 '17 at 19:24

Don't Panic

41,125
10
61
80

score 0 · Answer 2 · answered Sep 25 '17 at 19:15

0

Use a loop and array_merge:

$filteredArray = array();
foreach ($all as $array) {
   $filteredArray = array_merge($filteredArray, $array['itens']);
}
print_r($filteredArray);

answered Sep 25 '17 at 19:15

S.Gartmeier

476
5
14

score 0 · Answer 3 · answered Sep 25 '17 at 19:17

0

You can loop through your arrays and join them:

$filteredArray = array();

foreach($all as $items) {
    foreach($items["itens"] as $item) {
        array_push($filteredArray, $item);
    }
}

answered Sep 25 '17 at 19:17

dvr

885
5
20

score 0 · Answer 4 · answered Sep 25 '17 at 19:32

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

score 0 · Answer 5 · answered Apr 08 '21 at 02:48

Another unmentioned technique is to iterate the input array and push a variable number of elements into the output array.

Code: (Demo)

$result = [];
foreach ($all as $row) {
    array_push($result, ...$row['itens']);
}
var_export($result);

Output:

array (
  0 => 'item1',
  1 => 'item2',
  2 => 'item3',
  3 => 'item4',
  4 => 'item5',
  5 => 'item6',
  6 => 'item7',
  7 => 'item8',
  8 => 'item9',
)

Create a flat array of values from an array column containing array-type data

5 Answers5