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 — ishegg
– ishegg, Commented Sep 25, 2017 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
– mickmackusa ♦, Commented Apr 8, 2021 at 2:52

Don't Panic · Accepted Answer · 2017-09-25 19:50:57Z

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, 2017 at 19:50

answered Sep 25, 2017 at 19:24

Don't Panic

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Comments

S.Gartmeier · Accepted Answer · 2017-09-25 19:15:22Z

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, 2017 at 19:15

S.Gartmeier

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Comments

dvr · Accepted Answer · 2017-09-25 19:17:09Z

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, 2017 at 19:17

dvr

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Moeen Basra · Accepted Answer · 2017-09-25 19:32:26Z

0

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;
}

answered Sep 25, 2017 at 19:32

Moeen Basra

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Comments

mickmackusa · Accepted Answer · 2021-04-08 02:48:57Z

0

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',
)

answered Apr 8, 2021 at 2:48

mickmackusa♦

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