How to generate Combinations of fixed size from multiple arrays? - php

Question

I need to find all combinations of items in several arrays with fixed subset size. For example, I have the 3 arrays :
$A = array('A1','A2','A3');
$B = array('B1','B2','B3');
$C = array('C1','C2','C3');
I want to generate combinations of size 2 from the above arrays. Like:
$Combinations = array(
[0] => array('A1', 'B1'),
[1] => array('A1', 'C1'),
[2] => array('A2', 'B1'),
[3] => array('A2', 'C1')
);
This solution is generating all combinations, but does not seem to have size parameter in it.
Looking for help!

Answer 1

$A = array('A1','A2','A3');
$B = array('B1','B2','B3');
$C = array('C1','C2','C3');
$All = array();
foreach ($A as $key1=>$value1){
foreach ($B as $key2=>$value2){
$All[] = array($value1,$value2 );
}
foreach ($C as $key3=>$value3){
$All[] = array($value1,$value3 );
}
}
print_r($All);
Check output here : https://eval.in/574060

Answer 2

Finally, found a solution. With the following script, you can combine any number of arrays with any number of elements per a combination. Please read the comments in the code and try to understand what happens.
<?php
$A = array('A1', 'A2', 'A3');
$B = array('B1', 'B2', 'B3');
$C = array('C1', 'C2', 'C3');
$combinationCount = 5;
$itemsPerCombination = 2;
$array = ['A', 'B', 'C'];
$combinations = array();
for ($x = 0; $x < $combinationCount; $x++) {
//to keep temporary names of arrays which come in a combination
$arrays = array();
for ($y = 0; $y < $itemsPerCombination; $y++) {
$valid = false;
while (!$valid) {
//get a random array, check if it is already in our selection
$arrayElement = $array[rand(0, count($array) - 1)];
if (in_array($arrayElement, $arrays)) {
$valid = false;
continue;
}
$arrays[] = $arrayElement;
$valid = true;
}
}
$found = false;
while (!$found) {
//for each selection in our selected arrays, take a random element and add to the combination.
$combination = array();
foreach ($arrays as $arr) {
$temp=$$arr;
$combination[] = $temp[rand(0, count($temp) - 1)];
}
if (in_array($combination, $combinations)) {
$found = false;
continue;
}
$combinations[] = $combination;
$found = true;
}
}
echo(json_encode($combinations));
?>