sum specific values in a multidimensional array (php)

Question

I got a multidimensional array like this:

Totalarray
(
[0] => Array
    (
        [city] => NewYork
        [cash] => 1000
    )

[1] => Array
           


        

Answer 1

Using any more than one loop (or looping function) to sum the values is inefficient.

Here is a method that uses temporary keys to build the result array and then reindexes the result array after the loop terminates.

Code: (Demo)

$array=[
    ['city' => 'NewYork', 'cash' => '1000'],
    ['city' => 'Philadelphia', 'cash' => '2300'],
    ['city' => 'NewYork', 'cash' => '2000']
];

foreach($array as $a){
    if(!isset($result[$a['city']])){
        $result[$a['city']] = $a;  // store temporary city-keyed result array (avoid Notices)
    }else{
        $result[$a['city']]['cash'] += $a['cash'];  // add current value to previous value
    }
}
var_export(array_values($result));  // remove temporary keys