PHP array merge from unknown number of parameters

Question

I have an PHP array looking like this:

$array['my_data']['value'] = 'some value';
$array['my_own_data']['value'] = 'another value';
$array['different_data']['value'] = 'another value';

I need to use array_merge in PHP or such. The problem is that the number of first level keys are unknown. It could be 150 items, I don't know.

This would not work for me because of the unknown number of keys:

array_merge($array['my_data'], $array['my_own_data'], $array['different_data']);

Do I need a loop or are there something fancy?

Jahdiel

What do you want the final array to look like? – Servo

did you know that array_merge($array['my_data'], $array['my_own_data'], $array['different_data']); will result into an array containing $array['different_data']['value'] as array_merge will overwrite the array elements with equal key? – Tuition

What do you want to do? You've just told you've got some problem, but not what you need to retrieve from the original $array? The keys? The second keys? The values? – Fullfaced

Possible in PHP 5.6 using the ... operator. – Ungracious

Answer 1

This may do, if that's what you want:

$array = array_map('current', $array);

or possibly

$array = array_map(function ($a) { return $a['value']; }, $array);

This should give you

array('some value', 'another value', 'another value')

Servo

Answer 2

The problem is that the number of first level keys are unknown. It could be 150 items, I don't know.

That's a problem easy to solve.

If you want to know the number of keys of the first level:

$numberOfKeysOfTheFirstLevel = count($array);

There you know the number now. If you need actually their names, you can do so as well:

$keyNamesOfTheFirstLevel = array_keys($array);

So then you continued in your question:

This would not work for me because of the unknown number of keys: array_merge($array['my_data'], $array['my_own_data'], $array['different_data']);

The good news is, you don't need to know the number of keys to perform your array_merge operation:

call_user_func_array('array_merge', $array);

So regarding to what you wrote about in your question, this should answer it. However the result might not be what you expected. See the other answers as well please and please ask.

Fullfaced

Answer 3

Please try this:

$new_array = array();
foreach($array as $item) {
  $new_array[] = $item['value'];
};

Daves

Answer 4

// 1. your array should have different keys, otherwise it will have no effect
$array['my_data']['value1'] = 'some value';
$array['my_own_data']['value2'] = 'another value';
$array['different_data']['value3'] = 'another value';

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

will return

array(
  'value1' => 'some value', 
  'value2' => 'another value', 
  'value3' => 'another value', 
)

Otherwise, did you wanted something like this ?

array(
  'value' => array('some value', 'another value', 'another value')
)

Then you could do

$array['my_data']['value'] = 'some value';
$array['my_own_data']['value'] = 'another value';
$array['different_data']['value'] = 'another value';

$result = array();
// PHP <= 5.2
array_walk($array, create_function('&$item, $key, &$dest', '
    foreach ((array) $item as $subKey => $value) {
        if (!isset($dest[$subKey])) { $dest[$subKey] = array(); }
        $dest[$subKey][] = $value;
    }
'), & $result);
var_export($result);

Depressed

Answer 5

array_map(function($a){
    return $a['value'];
},$array);

for php5.2 and older:

function stuff($a){
    return $a['value'];
}
array_map('stuff',$array);

Assyriology

Answer 6

If I understand what you want, you could use array_map.

To change:

$a = array();
$a['x']['value'] = 1;
$a['y']['value'] = 3;
$a['z']['value'] = 3;

into:

array(3) {
 ["x"]=>
 int(1)
 ["y"]=>
 int(2)
 ["z"]=>
 int(3)
}

You could define a function:

function f($x) { return $x['value'];}

and use array_map:

$b = array_map(f, $a);

Screwball