How to Efficiently Sum Values in a Specific Column of a Multidimensional Array?

Sum Values in a Multidimensional Array Column

Multidimensional arrays present a challenge when it comes to summing specific columns. Consider the example array given:

$arr = [
    [0] => ['f_count' => 1, 'uid' => 105],
    [1] => ['f_count' => 0, 'uid' => 106],
    [2] => ['f_count' => 2, 'uid' => 107],
    [3] => ['f_count' => 0, 'uid' => 108],
    [4] => ['f_count' => 1, 'uid' => 109],
    [5] => ['f_count' => 0, 'uid' => 110],
    [6] => ['f_count' => 3, 'uid' => 111]
];

The desired output is 7, which is the sum of the f_count column.

Solution Without a Foreach Loop

PHP 5.5 and later provides two functions that simplify this task:

• array_column: Extracts a specific column from an array.
• array_sum: Sums the values in an array.

Using these functions, we can obtain the sum without a foreach loop:

$f_count_column = array_column($arr, 'f_count');
$sum = array_sum($f_count_column);

Alternative Approach: Restructuring the Query

Instead of retrieving a multidimensional array, we can restructure the query to return a one-dimensional array:

$query = "SELECT SUM(f_count) AS total_f_count FROM users WHERE gid=:gid";

$stmt = $pdo->prepare($query);
$stmt->execute([':gid' => $gid]);
$row = $stmt->fetch(PDO::FETCH_ASSOC);

$total_f_count = $row['total_f_count'];

The above is the detailed content of How to Efficiently Sum Values in a Specific Column of a Multidimensional Array?. For more information, please follow other related articles on the PHP Chinese website!