Common values in PHP Array - php

Question

I have two arrays
Array 1:
$strong_areas=array(
'192'=>57,
'187'=>43,
'121'=>85,
'198'=>74
);
Array 2:
$weak_areas=array(
'109'=>57,
'187'=>54,
'181'=>85,
'198'=>25
);
I need resultant array like this:
array(
'192'=>57, //57-0
'187'=>-11, //43-54
'121'=>85, //85-0
'198'=>49, //74-25
'109'=>-57, // 0-57
'181'=>-85, //0-85
)
What I tried so far:
//for common keys in both arrays
$temp=array_intersect_key($strong_areas,$weak_areas);
//for unique ones from first to second
$strong_final_array=array_diff_key($strong_areas, $weak_areas);
//for unique ones from second to first
$weak_final_array=array_diff_key($weak_areas, $strong_areas);
foreach ($weak_final_array as &$value){
$value *= (-1);
}
//returning final values for common keys in array
$common=array();
foreach($temp as $key => $value){
$common[$key]=$strong_areas[$key]-$weak_areas[$key];
}
//getting final results
$final_array=array_merge($strong_final_array,$weak_final_array,$common);
The question is, is the above procedure best practice or is there any easier way to do this?

Answer 1

You can use like this
$final_result = array();
foreach (array_keys($strong_areas + $weak_areas) as $join_key) {
$final_result[$join_key] = ( isset($strong_areas[$join_key]) ? $strong_areas[$join_key] : 0 ) - ( isset($weak_areas[$join_key]) ? $weak_areas[$join_key] : 0 );
}
print_r($final_result);
The output array is
Array
(
[192] => 57
[187] => -11
[121] => 85
[198] => 49
[109] => -57
[181] => -85
)

Answer 2

You should use native php function: array_merge_recursive and array_walk. The benefit is they're php core function (which is written in C) and execute faster than using php foreach.
// this will return array with keys combined from argument arrays,
// value will be scalar if key only exist in 1 argument,
// and value will be array if key exist in multiple arguments
$result_array = array_merge_recursive($strong_areas,$weak_areas);
// this step will walk through result array and change its array value
// into subtraction of elements
array_walk($result_array, function ($element) {
if (is_array($element)) {
return $element[0] - $element[1];
} else {
return $element;
}
});
It's just sample code. You can make it more fancy by yourself
Regards,