How to split an array into sub-arrays based on specific values ​​in php

Question

I have an array as shown below, what I wanted to do was create some arrays based on datepart like (2011-02-04):

Array
(
    [0] => Array
        (
            [avgvalue] => 0
            [maxvalue] => 0
            [minvalue] => 0
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-04T11:00:00.000Z
        )

    [1] => Array
        (
            [avgvalue] => 268.3
            [maxvalue] => 268.3
            [minvalue] => 268.3
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-04T12:00:00.000Z
        )

    [2] => Array
        (
            [avgvalue] => 268.391666667
            [maxvalue] => 268.4
            [minvalue] => 268.3
            [nrsamples] => 0.0288675134595
            [stddeviation] => 0.0288675134595
            [timestamp] => 2011-02-04T13:00:00.000Z
        )

    [3] => Array
        (
            [avgvalue] => 268.433333333
            [maxvalue] => 268.5
            [minvalue] => 268.4
            [nrsamples] => 0.0492365963918
            [stddeviation] => 0.0492365963918
            [timestamp] => 2011-02-04T14:00:00.000Z
        )

    [4] => Array
        (
            [avgvalue] => 268.5
            [maxvalue] => 268.5
            [minvalue] => 268.5
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-04T15:00:00.000Z
        )

    [5] => Array
        (
            [avgvalue] => 268.575
            [maxvalue] => 268.6
            [minvalue] => 268.5
            [nrsamples] => 0.0452267016867
            [stddeviation] => 0.0452267016867
            [timestamp] => 2011-02-04T16:00:00.000Z
        )

    [6] => Array
        (
            [avgvalue] => 268.616666667
            [maxvalue] => 268.7
            [minvalue] => 268.6
            [nrsamples] => 0.0389249472081
            [stddeviation] => 0.0389249472081
            [timestamp] => 2011-02-04T17:00:00.000Z
        )

    [7] => Array
        (
            [avgvalue] => 268.7
            [maxvalue] => 268.7
            [minvalue] => 268.7
            [nrsamples] => 0
            [stddeviation] => 0
                [timestamp] => 2011-02-04T18:00:00.000Z
        )

    [8] => Array
        (
            [avgvalue] => 268.741666667
            [maxvalue] => 268.8
            [minvalue] => 268.7
            [nrsamples] => 0.0514928650545
            [stddeviation] => 0.0514928650545
            [timestamp] => 2011-02-04T19:00:00.000Z
        )

    [9] => Array
        (
            [avgvalue] => 268.8
            [maxvalue] => 268.8
            [minvalue] => 268.8
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-04T20:00:00.000Z
        )

    [10] => Array
        (
            [avgvalue] => 268.883333333
            [maxvalue] => 268.9
            [minvalue] => 268.8
            [nrsamples] => 0.0389249472081
                [stddeviation] => 0.0389249472081
            [timestamp] => 2011-02-04T21:00:00.000Z
        )

    [11] => Array
        (
            [avgvalue] => 268.908333333
            [maxvalue] => 269
            [minvalue] => 268.9
            [nrsamples] => 0.0288675134595
            [stddeviation] => 0.0288675134595
            [timestamp] => 2011-02-04T22:00:00.000Z
        )

    [12] => Array
        (
            [avgvalue] => 269
            [maxvalue] => 269
            [minvalue] => 269
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-04T23:00:00.000Z
        )

    [13] => Array
        (
            [avgvalue] => 269.05
            [maxvalue] => 269.1
            [minvalue] => 269
            [nrsamples] => 0.0522232967867
            [stddeviation] => 0.0522232967867
            [timestamp] => 2011-02-05T00:00:00.000Z
        )

    [14] => Array
        (
            [avgvalue] => 269.1
            [maxvalue] => 269.1
            [minvalue] => 269.1
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-05T01:00:00.000Z
        )

    [15] => Array
        (
            [avgvalue] => 269.166666667
            [maxvalue] => 269.2
            [minvalue] => 269.1
            [nrsamples] => 0.0492365963917
            [stddeviation] => 0.0492365963917
            [timestamp] => 2011-02-05T02:00:00.000Z
        )

    [16] => Array
        (
            [avgvalue] => 269.2
            [maxvalue] => 269.2
            [minvalue] => 269.2
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-05T03:00:00.000Z
        )

    [17] => Array
        (
            [avgvalue] => 269.291666667
            [maxvalue] => 269.3
            [minvalue] => 269.2
            [nrsamples] => 0.0288675134595
            [stddeviation] => 0.0288675134595
            [timestamp] => 2011-02-05T04:00:00.000Z
        )

    [18] => Array
        (
            [avgvalue] => 269.333333333
            [maxvalue] => 269.4
            [minvalue] => 269.3
            [nrsamples] => 0.0492365963917
            [stddeviation] => 0.0492365963917
            [timestamp] => 2011-02-05T05:00:00.000Z
        )

    [19] => Array
        (
            [avgvalue] => 269.4
            [maxvalue] => 269.4
            [minvalue] => 269.4
            [nrsamples] => 0
            [stddeviation] => 0
            [timestamp] => 2011-02-05T06:00:00.000Z
        )
 )

The above list has an array. It has a timestamp, I blew the timestamp key, so I got the date and time separated separately, now I have a problem with splitting the array into subarrays. I wanted to have one array for 2011-02-04 (containing all values ​​for this date) and another array for 2011-02-05 (containing values ​​for all this date). This can be dynamic, I mean, dates can be even larger. So how can I do this.

I want this as:

array[0] => array(... list of all the values for 2011-02-04),
array[1] => array(...list of all values for 2011-02-05)

Stuck here, couldn't make it work. Please suggest.

Answer 1

, (, ,), :

$result = array();

foreach($array as $item) {
    $date = strstr($item['timestamp'], 'T', true);
    if(!array_key_exists($date, $result)) {
        $result[$date] = array();
    }
    $result[$date][] = $item;
}

: strstr, array_key_exists

ksort $result .