Merge and group by several arrays - php

Question

I need to merge associative arrays and group by the name. Say I have such 3 arrays:
ARRAY1
"/path/file.jpg" => 2,
"/path/file2.bmp" => 1,
"/file3.gif" => 5,
ARRAY2
"/path/file.jpg" => 1,
"/path/file2.bmp" => 1,
"/file3.gif" => 0,
ARRAY3
"/path/file.jpg" => 1,
"/path/file2.bmp" => 1,
I need to merge these arrays to one and group them by filepath and have result of sum of their values. Something like:
SELECT filename, SUM(val) FROM files
GROUP BY filename
But with multiple input arrays. Arrays are short (around 20 elements max). Each array might have different size.

Answer 1

[EDIT: I adapted the function (as suggested by John Green) to use func_get_args so you don't need to put all the seperate arrays in one array before you can use it.]
I think you could use the following function.
mergeArrays()
{
$return = array();
$arrays = func_get_args();
foreach ($arrays as $array) {
foreach ($array as $key => $val) {
if (array_key_exists($key, $array) {
$return[$key] += $val;
} else {
$return[$key] = $val;
}
}
}
return $return;
}

Answer 2

one possible way
$rtn = array();
foreach ($array1 as $key=>$val)
{
$rtn[$key]+=$val;
}
foreach ($array2 as $key=>$val)
{
$rtn[$key]+=$val;
}
foreach ($array2 as $key=>$val)
{
$rtn[$key]+=$val;
}
the above will assign the filename, SUM(val) as an associative array into $rtn

Answer 3

You can use a RecursiveArrayIterator
$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($paths));
foreach ($iterator as $path => $value) {
$summed[$path] = isset($summed[$path]) ? $summed[$path] + $value : $value;
}
print_r($summed);
or array_walk_recursive and a Closure
$summed = array();
array_walk_recursive($paths, function($value, $path) use (&$summed) {
$summed[$path] = isset($summed[$path]) ? $summed[$path] + $value : $value;
});
Both will give
Array
(
[/path/file.jpg] => 4
[/path/file2.bmp] => 3
[/file3.gif] => 5
)