Using implode to group information from acquired in a whileloop (problem solved)

Question

Solved the problem thanks to all of your tips. Thanks a lot for all the answers. d(^_^d)

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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.

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<?
$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

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 2

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 );
}

Answer 3

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";