PHP groups two-dimensional arrays according to key

We often get a two-dimensional array and find that the result is somewhat different from what we want. We may need to group the array according to a certain field in the two-dimensional array.

Let’s first look at the following array,

Array
(
[0] => Array
(
[id] => 1
[wo_id] => 2
[evaluate_id] => 1
[type] => 分组1
[ctime] => 2016-12-02 11:39:34
)
[1] => Array
(
[id] => 2
[wo_id] => 31
[evaluate_id] => 2
[type] => 分组1
[ctime] => 2016-12-12 11:39:50
)
[2] => Array
(
[id] => 3
[wo_id] => 31
[evaluate_id] => 4
[type] => 分组2
[ctime] => 2016-12-02 11:40:01
)
[3] => Array
(
[id] => 4
[wo_id] => 2
[evaluate_id] => 5
[type] => 分组2
[ctime] => 2016-12-07 10:21:40
)
[4] => Array
(
[id] => 5
[wo_id] => 2
[evaluate_id] => 3
[type] => 分组2
[ctime] => 2016-12-07 10:21:51
)
[5] => Array
(
[id] => 6
[wo_id] => 2
[evaluate_id] => 2
[type] => 分组3
[ctime] => 2016-12-07 10:21:56
)
[6] => Array
(
[id] => 7
[wo_id] => 4
[evaluate_id] => 2
[type] => 分组3
[ctime] => 2016-12-07 10:22:10
)
)

Here is a very typical example. If I want to process the data in the array separately according to type (grouping), if not grouped, the loop may be very redundant, so there is The following grouping function:

public static function array_group_by($arr, $key)
{
$grouped = [];
foreach ($arr as $value) {
$grouped[$value[$key]][] = $value;
}
// Recursively build a nested grouping if more parameters are supplied
// Each grouped array value is grouped according to the next sequential key
if (func_num_args() > 2) {
$args = func_get_args();
foreach ($grouped as $key => $value) {
$parms = array_merge([$value], array_slice($args, 2, func_num_args()));
$grouped[$key] = call_user_func_array('array_group_by', $parms);
}
}
return $grouped;
}

$arr: two-dimensional array

$key: the key that needs to be grouped

The result is:

Array
(
[分组2] => Array
(
[0] => Array
(
[id] => 1
[wo_id] => 2
[evaluate_id] => 1
[ctime] => 2016-12-02 11:39:34
[type] => 分组2
)
[1] => Array
(
[id] => 2
[wo_id] => 31
[evaluate_id] => 2
[ctime] => 2016-12-12 11:39:50
[type] => 分组2
)
[2] => Array
(
[id] => 3
[wo_id] => 31
[evaluate_id] => 4
[ctime] => 2016-12-02 11:40:01
[type] => 分组2
)
)
[分组1] => Array
(
[0] => Array
(
[id] => 4
[wo_id] => 2
[evaluate_id] => 5
[ctime] => 2016-12-07 10:21:40
[type] => 分组1
)
[1] => Array
(
[id] => 5
[wo_id] => 2
[evaluate_id] => 3
[ctime] => 2016-12-07 10:21:51
[type] => 分组1
)
)
)