How to Create complex Array Structure in PHP - php

Question

I have to make this kind of structure in array;
We have three ( 3 ) variables which creates this structure:
$numberOfParticipants = 38; // 38 is example
$numberOfParticipantsPerHeat = 8 // 8 is example
$numberOfHeats = 5; // 5 is example
Based on this variables I have this table:
The problem is that, I can't place the ' - ' or null after 31 OR 38. The task is that i have to make the arrays of array "almost equal" like the photo and must depend on the variables above. By the way, after I create the correct list I will slice the array to 5 or 6 or whatever parts I need this is not the problem, the problem is that I have to parse the list like this first. This is what I tried so far:
$calc1 = (int)round($numberOfParticipants * $numberOfParticipantsPerHeat, -1); //First round the numberOfParticipants to closest integer by 10
$readyArr = [];
for ($i = 1; $i <= $calc1; $i++) {
if ($i <= $numberOfParticipants) {
$readyArr[$i] = $i;
} else {
$readyArr[$i] = null;
}
}
The problem with this snippet is that it places the null at the end of the list not after 31, or based on the var.
This is the result I have:
array:40 [▼
1 => 1
2 => 2
3 => 3
4 => 4
5 => 5
6 => 6
7 => 7
8 => 8
9 => 9
10 => 10
11 => 11
12 => 12
13 => 13
14 => 14
15 => 15
16 => 16
17 => 17
18 => 18
19 => 19
20 => 20
21 => 21
22 => 22
23 => 23
24 => 24
25 => 25
26 => 26
27 => 27
28 => 28
29 => 29
30 => 30
31 => 31
32 => 32
33 => 33
34 => 34
35 => 35
36 => 36
37 => 37
38 => 38
39 => null
40 => null
]
The Array after partition I want should be:
array(
0 => array(0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5, 5 => 6, 6 => 7, 7 => 8,),
1 => array(0 => 9, 1 => 10, 2 => 11, 3 => 12, 4 => 13, 5 => 14, 6 => 15, 7 => 16,),
2 => array(0 => 17, 1 => 18, 2 => 19, 3 => 20, 4 => 21, 5 => 22, 6 => 23, 7 => 24,),
3 => array(0 => 25, 1 => 26, 2 => 27, 3 => 28, 4 => 29, 5 => 30, 6 => 31, 7 => null,),
4 => array(0 => 32, 1 => 33, 2 => 34, 3 => 35, 4 => 36, 5 => 37, 6 => 38, 7 => null,),
);
Every help, every clue will be highly appreciated.

Answer 1

There are two things you need to know about the target structure:
How many players are in the first (which will always be the largest, if only by one) set.
$playersPerHeat = ceil($numberOfParticipants / $numberOfHeats);
// note this replaces your hard-coded $numberOfParticipantsPerHeat
You also need to know how many heats actually have that many, that is how many heats are actually full.
$fullHeats = $numberOfParticipants % $numberOfHeats ?: $numberOfHeats;
// The ?: bit means that if we get zero (ie. all equal heats), then we
// count all the heats instead, since they're all full.
Now it's easy!
$players = range(1,$numberOfParticipants);
$heats = array_merge(
array_chunk(
array_slice($players, 0, $fullHeats * $playersPerHeat),
$playersPerHeat
),
array_chunk(
array_slice($players, $fullHeats * $playersPerHeat),
$playersPerHeat - 1
)
);
That's it! Demo