Combine 2 arrays into 2d array without losing data - php

Question

I have 2 arrays and want to combine into third array with one array as key and another as value. I tried to use array_combine(), but the function will eliminate all the repeated keys, so I want the result array as a 2d array. The sample array is as below:
$keys = {0,1,2,0,1,2,0,1,2};
$values = {a,b,c,d,e,f,g,h,i};
$result = array(
[0]=>array(0=>a,1=>b,2=>c),
[1]=>array(0=>d,1=>e,2=>f),
[2]=>array(0=>g,1=>h,2=>i)
);
//What i am using right now is:
$result = array_combine($keys,$values);
But it only returns array(0=>g,2=>h,3=>i). Any advice would be appreciated!

Answer 1

You can do it like below:-
<?php
$keys = array(0,1,2,0,1,2,0,1,2);
$values = array('a','b','c','d','e','f','g','h','i');
$values = array_chunk($values,count(array_unique($keys)));
foreach($values as &$value){
$value = array_combine(array_unique($keys),$value);
}
print_r($values);
https://eval.in/859753

Answer 2

Yes the above is working and i give upvote too for this but i dont know why you combine into the foreach loop its not necessary. The results are given in only in second line. Can you describe?
<?php
$keys = array(0,1,2,0,1,2,0,1,2);
$values = array('a','b','c','d','e','f','g','h','i');
$v = array_chunk($values,count(array_unique($keys)));
echo "<pre>";print_r($v);
?>
https://eval.in/859759

Answer 3

As a more flexible/robust solution, push key-value pairs into new rows whenever the key's value is already in the currently targeted row. In other words, there will never be an attempt to write a key into a row that already contains that particular key.
This can be expected to be highly efficient because there are no iterated function calls ...no function calls at all, really.
Code: (Demo)
$result = [];
foreach ($keys as $i => $key) {
$counter[$key] = ($counter[$key] ?? -1) + 1;
$result[$counter[$key]][$key] = $values[$i];
}
var_export($result);