Generating a series of sequential arrays of version-like values in PHP

Question

I've been banging my head against this problem for a while. I feel like it should be simple, but I'm having a hard time coming up with a solution.

I'm looking to pre-populate a database, and I need to create SQL statements with some foreign key values. It would be tedious to hand-code them, so naturally I decided to do it in code.

What I want are series of arrays that have values as such:

[1]
[2]
[3]
[1,1]
[1,2]
[1,3]
[2,1]
[2,2]
...
[1,1,1]
[1,1,2]
[1,1,3]
...
[3,1,1]
...
[3,3,3]

I want to specify the number of values in the array, and the numerical value at which it causes the preceeding value to roll over.

In the example I gave above, it would be like generate(3,3), since the maximum number of elements is 3, and the highest value is 3.

How could I write some code that would give me this series of arrays?

I hope you have tried something. So kindly add your code effort. As you know without code-effort your question may got closed/got down-voted. — Alive to die - Anant, Oct 29 '20 at 04:22
Hope this will help you:https://stackoverflow.com/questions/19067556/php-algorithm-to-generate-all-combinations-of-a-specific-size-from-a-single-set the correct answer getting all possible combination based on size. You can take reference of code and convert it to fir your requirement — Alive to die - Anant, Oct 29 '20 at 04:26
https://stackoverflow.com/questions/10834393/php-how-to-get-all-possible-combinations-of-1d-array — Alive to die - Anant, Oct 29 '20 at 04:27

Nick · Accepted Answer · 2020-10-29T04:39:06.450

This is a recursive function that will generate each of the combinations of the ranges up to the maximum value, with elements in each array from 1 to the number specified:

function generate($elements, $maxvalue) {
    if ($elements == 0) return array();
    $result = array();
    foreach (range(1, $maxvalue) as $el) {
        $result[] = array($el);
    }
    foreach (range(1, $maxvalue) as $el) {
        foreach (generate($elements - 1, $maxvalue) as $arr) {
            $result[] = array($el, ...$arr);
        }
    }
    return $result;
}

$combs = generate(3, 3);

Output is too long to show here but can be seen in this demo on 3v4l.org

Note for PHP < 7.4, replace

$result[] = array($el, ...$arr);

with

$result[] = array_merge(array($el), $arr);

Jeto · Answer 2 · 2020-10-29T05:40:09.073

Here's a version using generators (which may be slightly easier on memory than pure arrays):

function generate(int $elementsCount, int $maxValue, array $current = []): \Generator
{
    for ($value = 1; $value <= $maxValue; $value++) {
        yield [...$current, $value];
    }
    if ($elementsCount > 1) {
        for ($value = 1; $value <= $maxValue; $value++) {
            yield from generate($elementsCount - 1, $maxValue, [...$current, $value]);
        }
    }
}

Exemple usage + debug/print:

$combinations = generate(3, 3);
print_r(iterator_to_array($combinations, false));

Demo

Generating a series of sequential arrays of version-like values in PHP

2 Answers2