Pivot array based on row count - php

Question

I have the following:
$array = array(1,2,3,4,5,6);
I need to "pivot" it to get :
Array ( [0] => 1 [1] => 4 [2] => 2 [3] => 5 [4] => 3 [5] => 6 )
by "pivot" I mean, let's imagine that the array is stored a 2 x 3 matrix (2 rows, and 3 columns). My goal is to pivot it, so that the matrix is now a 3 x 2 matrix (3 rows, 2 columns)
for that of course I need an extra argument, let's say "number of rows" (in this case this is like 2 rows)
I did the following:
function pivotArray($array, $nbrRows)
{
$countTotal = count($array);
$countCols = $countTotal / $nbrRows;
$chunk = array_chunk($array,$countCols);
$out = array();
for ($row=0;$row<$nbrRows;$row++) {
for ($col=0;$col<$countCols;$col++) {
$out[$col][$row] = $chunk[$row][$col];
}
}
$arraySingle = call_user_func_array('array_merge', $out);
return $arraySingle;
}
it works as designed but I wonder whether there is a better way to do that ? for instance avoiding the 2 for loops ? and also avoid the array_merge ?

Answer 1

Instead of reporcessing the array a few times, this code builds an intermediate array and spreads the elements based on $position % $countCols. I've also introduced ceil() to the count of columns in case there is an odd number of elements...
function pivotArray($array, $nbrRows)
{
$countTotal = count($array);
$countCols = ceil($countTotal / $nbrRows);
$arraySingle = [];
foreach ( $array as $position => $value ) {
$arraySingle[$position % $countCols][] = $value;
}
return array_merge(...$arraySingle);
}