PHP multidimensional array sort by value - php

Question

Regarding this multidimensional array:
[
(int) 7 => [
(int) 0 => [
(int) 0 => '12:45',
(int) 1 => 'E1',
(int) 2 => 'B EXTREME 30'
],
(int) 1 => [
(int) 0 => '10:15',
(int) 1 => 'E1',
(int) 2 => 'B SHAPE 30'
],
],
(int) 1 => [
(int) 0 => [
(int) 0 => '09:30',
(int) 1 => 'E2',
(int) 2 => 'CYCLING VIRTUAL 50'
],
(int) 1 => [
(int) 0 => '10:30',
(int) 1 => 'E1',
(int) 2 => 'BODY PUMP VIRTUAL 60'
],
(int) 2 => [
(int) 0 => '11:45',
(int) 1 => 'E1',
(int) 2 => 'BODY BALANCE VIRTUAL 60'
],
],
(int) 2 => [
(int) 0 => [
(int) 0 => '14:45',
(int) 1 => 'E2',
(int) 2 => 'CYCLING VIRTUAL 50'
],
(int) 1 => [
(int) 0 => '17:00',
(int) 1 => 'E1',
(int) 2 => 'POSTURA ALONGAMENTO 60'
],
(int) 2 => [
(int) 0 => '09:15',
(int) 1 => 'E1',
(int) 2 => 'BODY PUMP 50'
],
]
]
The first key, of each first level array, are days of the week (day 7, day 1 and day 2).
The arrays inside each first level array contain hour (09:45), rooms (E1) and description (B EXTREME 30).
I tried to sort this multidimensional array by the second levels array hour value.
I used usort(), ksort(), array_multisort(), and some custom made functions for sorting the array as i need without luck.
The inside arrays must be sorted by ascending order, like this (example with day 2):
09:15 -> 14:45 -> 17:00
Does anyone knows how can i achieve this?

Answer 1

Assuming your data is called $data. Iterate the outer array, and apply a sort on each mid-level array, based on the time-part (in the innermost arrays). As your times are always formatted as "hh:ss", a string comparison in the usort callback does the job:
foreach ($data as &$events) {
usort($events, function($a, $b) {
return strcmp($a[0], $b[0]);
});
}
Note the & in the foreach: this makes sure you sort the original data, and not a copy of it.
If you want to create a new array, let's say $result, then do this (no & here!):
foreach ($data as $day => $events) {
usort($events, function($a, $b) {
return strcmp($a[0], $b[0]);
});
$result[$day] = $events;
}

Answer 2

usort — Sort an array by values using a user-defined comparison function.
Lets create a function where we compare time of two events.
This is part of your array
$array = [
2 => [
0 => [
0 => '14:45',
1 => 'E2',
2 => 'CYCLING VIRTUAL 50'
],
1 => [
0 => '17:00',
1 => 'E1',
2 => 'BODY PUMP VIRTUAL 60'
],
2 => [
0 => '09:15',
1 => 'E1',
2 => 'BODY BALANCE VIRTUAL 60'
],
],
];
This is an example how to sort items for one day (day 2)
usort($array[2], function ($a, $b) {
$time_a = strtotime($a[0]); // convert string to a unix timestamp to compare int
$time_b = strtotime($b[0]);
return $time_a - $time_b;
});
Output using print_r($array);
Array
(
[2] => Array
(
[0] => Array
(
[0] => 09:15
[1] => E1
[2] => BODY BALANCE VIRTUAL 60
)
[1] => Array
(
[0] => 14:45
[1] => E2
[2] => CYCLING VIRTUAL 50
)
[2] => Array
(
[0] => 17:00
[1] => E1
[2] => BODY PUMP VIRTUAL 60
)
)
)
To sort all days we do in a loop, passing each day array as a reference using &:
foreach ($array as &$day) {
usort($day, function ($a, $b) {
$time_a = strtotime($a[0]);
$time_b = strtotime($b[0]);
return $time_a - $time_b;
});
}