How to merge values of the second level of two arrays with different number of keys?

Question

I have following arrays: ``` $array1 = " Array ( [0] => Array ( [0] => Value1 [1] => Value2 ) [1] => Array ( [0] => Value3 [1] => Value4 ) [2] => Array ( [0] => Value5 [1] => Value6 ) ... [999] => Array ( [0] => Value7 [1] => Value8 ) ) ``` and ``` $array2 = " Array ( [0] => Array ( [0] => ValA [1] => ValB [2] => ValC [3] => ValD ) [1] => Array ( [0] => ValE [1] => ValF [2] => ValG [3] => ValH ) [2] => Array ( [0] => ValI [1] => ValJ [2] => ValK [3] => ValL ) ... [999] => Array ( [0] => ValM [1] => ValN [2] => ValO [3] => ValP ) ) ``` I would like to merge both arrays so that in the end I have the same structure, number of keys in the first level, but the values would be "joined" in the second level just like we can see in the following result array: ``` $array3 = " Array ( [0] => Array ( [0] => Value1 [1] => Value2 [2] => ValA [3] => ValB [4] => ValC [5] => ValD ) [1] => Array ( [0] => Value3 [1] => Value4 [2] => ValE [3] => ValF [4] => ValG [5] => ValH ) [2] => Array ( [0] => Value5…

Accepted Answer

There is an "elegant" way to resolve your issue (it will require, however, that both of your arrays must have same count of items):

```
$result = array_map('array_merge', $array1, $array2);
```

Check the fiddle.

Answering to your question: `array_merge_recursive()` will fail because it appends numeric keys, not merging them:

If the input arrays have the same string keys, then the values for these keys are merged together into an array, and this is done recursively, so that if one of the values is an array itself, the function will merge it with a corresponding entry in another array too. If, however, the arrays have the same numeric key, the later value will not overwrite the original value, but will be appended.

How to merge values of the second level of two arrays with different number of keys?

Solution

Problem