How to sum all column values in multi-dimensional array?

Question

How can I add all the columnar values by associative key? Note that key sets are dynamic.

Input array:

Arr         


        

Answer 1

We need to check first if array key does exist.

CODE:

$sum = array();
foreach ($array as $key => $sub_array) {
    foreach ($sub_array as $sub_key => $value) {

        //If array key doesn't exists then create and initize first before we add a value.
        //Without this we will have an Undefined index error.
        if( ! array_key_exists($sub_key, $sum)) $sum[$sub_key] = 0;

        //Add Value
        $sum[$sub_key]+=$value;
    }
}
print_r($sum);

OUTPUT With Array Key Validation:

Array
(
    [gozhi] => 10
    [uzorong] => 1
    [ngangla] => 8
    [langthel] => 10
)

OUTPUT Without Array Key Validation:

Notice: Undefined index: gozhi in F:\web\index.php on line 37

Notice: Undefined index: uzorong in F:\web\index.php on line 37

Notice: Undefined index: ngangla in F:\web\index.php on line 37

Notice: Undefined index: langthel in F:\web\index.php on line 37

Array
(
    [gozhi] => 10
    [uzorong] => 1
    [ngangla] => 8
    [langthel] => 10
)

This is a bad practice although it prints the output. Always check first if key does exist.