如何根据特定键的值（在本例中为日期）对内部数组中的数组元素进行分组？

Question

I've an associative array called $events as follows (following is the output of print_r($events);) :

Note : The actual array is very large in size. For demonstration purpose I've put few elements from it.

Array
(
    [0] => Array
        (
            [group_name] => 
            [event_id] => 201
            [module_id] => event
            [user_id] => 991
            [title] => Zenda Vandan
            [location] => Satara, Maharashtra, India
            [country_iso] => MS
            [country_child_id] => 0
            [postal_code] => 
            [city] => 
            [time_stamp] => 1428315119 // 6 April 2015
        )

    [1] => Array
        (
            [group_name] => 
            [event_id] => 235
            [module_id] => event
            [user_id] => 901
            [title] => Bootstrap Feed Page
            [location] => Pune, Maharashtra, India
            [country_iso] => MS
            [country_child_id] => 0
            [postal_code] => 
            [city] => 
            [time_stamp] => 1436856285 // 14 July 2015
        )

    [2] => Array
        (
            [rsvp_id] => 0
            [event_id] => 236
            [module_id] => event
            [user_id] => 901
            [title] => Multiple Events
            [location] => Pune, Maharashtra, India
            [country_iso] => MS
            [country_child_id] => 0
            [postal_code] => 
            [city] => 
            [time_stamp] => 1436856356 // 14 July 2015
         )
     [3] => Array
        (
            [rsvp_id] => 0
            [event_id] => 237
            [module_id] => event
            [user_id] => 901
            [title] => Many Events
            [location] => Sangli, Maharashtra, India
            [country_iso] => MS
            [country_child_id] => 0
            [postal_code] => 
            [city] => 
            [time_stamp] => 1436856356 // 14 July 2015
         )
)

I want to group all array elements date-wise i.e. from time stamp values the events coming on same date should be grouped together. Following should be the desired resultant array in above case.

Array
(
    ['14 Jul, Tuesday'] => Array 
        (
            [0] => Array
                (
                    [group_name] => 
                    [event_id] => 235
                    [module_id] => event
                    [user_id] => 901
                    [title] => Bootstrap Feed Page
                    [location] => Pune, Maharashtra, India
                    [country_iso] => MS
                    [country_child_id] => 0
                    [postal_code] => 
                    [city] => 
                    [time_stamp] => 1436856285 // 14 July 2015
                )

                [1] => Array
                (
                    [rsvp_id] => 0
                    [event_id] => 236
                    [module_id] => event
                    [user_id] => 901
                    [title] => Multiple Events
                    [location] => Pune, Maharashtra, India
                    [country_iso] => MS
                    [country_child_id] => 0
                    [postal_code] => 
                    [city] => 
                    [time_stamp] => 1436856356 // 14 July 2015
                 )
                 [2] => Array
                (
                    [rsvp_id] => 0
                    [event_id] => 237
                    [module_id] => event
                    [user_id] => 901
                    [title] => Many Events
                    [location] => Sangli, Maharashtra, India
                    [country_iso] => MS
                    [country_child_id] => 0
                    [postal_code] => 
                    [city] => 
                    [time_stamp] => 1436856356 // 14 July 2015
                 )
        )

        ['14 Apr, Monday'] => Array 
        (
            [0] => Array
                (
                    [group_name] => 
                    [event_id] => 201
                    [module_id] => event
                    [user_id] => 991
                    [title] => Zenda Vandan
                    [location] => Satara, Maharashtra, India
                    [country_iso] => MS
                    [country_child_id] => 0
                    [postal_code] => 
                    [city] => 
                    [time_stamp] => 1428315119 // 6 April 2015
                )
            )

)

How should I get this in an optimum way?

Thanks in advance.

Answer 1

Pretty straight forward...

$result = [];
foreach($events as $event){
    //I included year in the date format so you years dont all end up in the same sub array
    $result[date('d M, l Y',$event['time_stamp'])][]=$event;
}
print_r($result);