combine 2 array with same key into 1 array - php

Question

I have 2 Array:
$arr1 = Array (
[2] => Array ( [0] => 41000 [1] => 31079 )
[3] => Array ( [0] => 42963 [1] => 41189 )
)
$arr2 = Array (
[2] => Array ( [0] => 40213 [1] => 42054 )
[3] => Array ( [0] => 42998 [1] => 34567 )
)
I want to combine these two arrays to this array with same key:
$arr3 = Array (
[2] => Array ( [0] => 40213 [1] => 42054 [2] => 41000 [3] => 31079 )
[3] => Array ( [0] => 42998 [1] => 34567 [2] => 42963 [3] => 41189 )
)
I tried almost anything (merge, combine, join) but I can't figure it out. Any suggestions?

Answer 1

This is a nice and easy thing to do.
$arr1 = [2 => [0 => 41000, 1 => 31079], 3 => [0 => 42963, 1 => 41189]];
$arr2 = [2 => [0 => 40213, 1 => 42054], 3 => [0 => 42998, 1 => 34567]];
function addArray(&$bucket, $water)
{
foreach ($water as $key => $drop) {
$bucket[$key] = array_merge($bucket[$key] ?? [], $drop);
}
}
$combined = [];
addArray($combined, $arr1);
addArray($combined, $arr2);
var_export($combined);
See a PHP fiddle here.
The output is:
array (
2 =>
array (
0 => 41000,
1 => 31079,
2 => 40213,
3 => 42054,
),
3 =>
array (
0 => 42963,
1 => 41189,
2 => 42998,
3 => 34567,
),
)
How does it work? I wrote a little function that would add the input arrays to an array that combines all arrays.

Answer 2

$arr1 = array(
2 => array(41000, 31079),
3 => array(42963, 41189)
);
$arr2 = array(
2 => array(40213, 42054),
3 => array(42998, 34567)
);
$arr3 = array();
foreach($arr1 as $key => $values){
if(!isset($arr3[$key])){
$arr3[$key] = array();
}
$arr3[$key] = array_merge($arr3[$key], $values);
}
foreach($arr2 as $key => $values){
if(!isset($arr3[$key])){
$arr3[$key] = array();
}
$arr3[$key] = array_merge($arr3[$key], $values);
}
echo '<pre>';
print_r($arr3);
Prints:
Array
(
[2] => Array
(
[0] => 41000
[1] => 31079
[2] => 40213
[3] => 42054
)
[3] => Array
(
[0] => 42963
[1] => 41189
[2] => 42998
[3] => 34567
)
)