生成一个按键分组并获取另一个键的SUM的新数组

Question

我想采用以下数组并生成一个新数组，该数组将所有具有相同ID的相同键组合在一起，同时获取视图的SUM并仅获取最后一个DATE。

原始数组

Array (
[0] => Array (
        [id] => 10
        [views] => 276
        [date] => 2012-01-30 10:55:00
        [total] => N
    )
[1] => Array (
        [id] => 40
        [views] => 287
        [date] => 2012-01-27 10:00:29
        [total] => Y
    )
[2] => Array (
        [id] => 40
        [views] => 824
        [date] => 2012-01-29 14:40:45
        [total] => Y
    )
[3] => Array (
        [id] => 42
        [views] => 723
        [date] => 2012-01-28 20:15:58
        [total] => N
    )
[4] => Array (
        [id] => 43
        [views] => 428
        [date] => 2012-01-28 17:14:31
        [total] => N
    )
[5] => Array (
        [id] => 45
        [views] => 174
        [date] => 2012-01-20 18:01:11
        [total] => N
    )
)

新数组

Array (
[0] => Array (
        [id] => 10
        [views] => 276
        [date] => 2012-01-30 10:55:00
        [total] => N
    )
[1] => Array (
        [id] => 40
        [views] => 1111
        [date] => 2012-01-29 14:40:45
        [total] => Y
    )
[2] => Array (
        [id] => 42
        [views] => 723
        [date] => 2012-01-28 20:15:58
        [total] => N
    )
[3] => Array (
        [id] => 43
        [views] => 428
        [date] => 2012-01-28 17:14:31
        [total] => N
    )
[4] => Array (
        [id] => 45
        [views] => 174
        [date] => 2012-01-20 18:01:11
        [total] => N
    )
)

Answer 1

function last($a, $b) {
  if (strtotime($a) > strtotime($b))
    return $a;
  else
    return $b;
}

$new_array = array();
foreach ($original_array as $data) {
  if (array_key_exists($data['id'], $new_array)) {
    $new_array[$data['id']]['views'] += $data['views'];
    $new_array[$data['id']]['date'] = last($new_array[$data['id']]['date'], $data['date']);
  } else
    $new_array[$data['id']] = $data;
}
$new_array = array_values($new_array);