Using implode to group information from acquired in a whileloop - php

Question

I am having the following problem. I have the numbers 1/2/3/4/5/6 and I want to separate them into two groups 1/3/5 and 2/4/6. The selection must take place based on the position. This part works ok. The problem comes when I want to group them again, when I use the implode function; it only sees the last number that was stored. I know it has something to do with me using this notation (I chose this way since the amount of numbers to classify varies every time):
$q++;
$row0 = $row0 + 2;
$row1 = $row1 + 2;
but I can't figure a way to fix it or another way to get the same result. Hopefully someone here can point me in the right direction. I left the complete code below.
<?
$string = "1/2/3/4/5/6";
$splitted = explode("/",$string);
$cnt = count($splitted);
$q=0;
$row0=0;
$row1=1;
while($cnt > 2*$q)
{
$p_row = implode(array($splitted[$row0]));
echo "$p_row <br>";
$i_row = implode(array($splitted[$row1]));
echo "$i_row <br>";
$q++;
$row0 = $row0 + 2;
$row1 = $row1 + 2;
}
$out = "implode(',', $i_row)";
var_dump($out);
?>

Answer 1

I missread the problem it seems. Instead I give this optimization.
$string = "1/2/3/4/5/6";
$splitted = explode("/", $string);
$group = array();
for ($index = 0, $t = count($splitted); $index < $t; ++$index) {
$group[$index & 1][] = $splitted[$index];
}
$oddIndex = $group[0]; //start with index 1
$evenIndex = $group[1]; //start with index 2
echo "odd index: "
. implode('/', $oddIndex)
. "\neven index: "
. implode('/', $evenIndex)
. "\n";

Answer 2

You can split the array into groups using % on loop index. Put each group in separate array. Here is example:
<?php
$string = "1/2/3/4/5/6";
$splitted = explode("/",$string);
$group_odd = array(); ## all odd elements of $splitted come here
$group_even = array(); ## all even elements of $splitted come here
for ($index = 0; $index < count($splitted); ++$index) {
## if number is divided by 2 with rest then it's odd
## but we've started calculation from 0, so we need to add 1
if (($index+1) % 2) {
$group_odd[] = $splitted[$index];
}
else {
$group_even[] = $splitted[$index];
}
}
echo implode('/', $group_odd), "<br />"; ## outputs "1/3/5<br />"
echo implode('/', $group_even), "<br />"; ## outputs "2/4/6<br />"
print_r($group_odd);
print_r($group_even);
?>

Answer 3

Based on their position? So, split based on the evenness/oddness of their index in the array?
Something like this?
<?php
$string = "1/2/3/4/5/6";
list( $evenKeys, $oddKeys ) = array_split_custom( explode( '/', $string ) );
echo '<pre>';
print_r( $evenKeys );
print_r( $oddKeys );
function array_split_custom( array $input )
{
$evens = array();
$odds = array();
foreach ( $input as $index => $value )
{
if ( $index & 1 )
{
$odds[] = $value;
} else {
$evens[] = $value;
}
}
return array( $evens, $odds );
}