How to merge two arrays by summing the merged values [duplicate]
$sums = array();foreach (array_keys($a1 + $a2) as $key) { $sums[$key] = (isset($a1[$key]) ? $a1[$key] : 0) + (isset($a2[$key]) ? $a2[$key] : 0);}You could shorten this to the following using the error suppression operator, but it should be considered ugly:
$sums = array();foreach (array_keys($a1 + $a2) as $key) { $sums[$key] = @($a1[$key] + $a2[$key]);}Alternatively, some mapping:
$keys = array_fill_keys(array_keys($a1 + $a2), 0);$sums = array_map(function ($a1, $a2) { return $a1 + $a2; }, array_merge($keys, $a1), array_merge($keys, $a2));Or sort of a combination of both solutions:
$sums = array_fill_keys(array_keys($a1 + $a2), 0);array_walk($sums, function (&$value, $key, $arrs) { $value = @($arrs[0][$key] + $arrs[1][$key]); }, array($a1, $a2));I think these are concise enough to adapt one of them on the spot whenever needed, but to put it in terms of a function that accepts an unlimited number of arrays and sums them:
function array_sum_identical_keys() { $arrays = func_get_args(); $keys = array_keys(array_reduce($arrays, function ($keys, $arr) { return $keys + $arr; }, array())); $sums = array(); foreach ($keys as $key) { $sums[$key] = array_reduce($arrays, function ($sum, $arr) use ($key) { return $sum + @$arr[$key]; }); } return $sums;}
My contribution:
function array_merge_numeric_values(){ $arrays = func_get_args(); $merged = array(); foreach ($arrays as $array) { foreach ($array as $key => $value) { if ( ! is_numeric($value)) { continue; } if ( ! isset($merged[$key])) { $merged[$key] = $value; } else { $merged[$key] += $value; } } } return $merged;}Pass as many arrays to it as you want. Feel free to add some more defense, ability to accept multidimensional arrays, or type checking.