Display table values vertically while keeping table structure

php, transpose

Solution

EDITED: This is harder than I thought and I messed it up the first time (or two). It should work now.

Let's say you have your table structure stored in a two dimensional array:

$data = array(
  array('a', 'b', 'c', 'd', 'e'),
  array('f', 'g', 'h', 'i', 'j'),
  array('k', 'l', 'm', 'n', 'o'),
  array('p', 'q', 'r')
);

Since you want to keep the same "shape" you need to determine the dimensions of the table. To do this we can take the `count` of the first row, since we know that the first row must be the maximum width of the table. The height is just the number of elements in the array.

$width = count($data[0]); // 5
$height = count($data);   // 4

We also need the total number of elements, but we can overestimate by taking $width * $height.

$total = $width * $height; // 20

Then it's really just a little math to calculate where things go. We have to use a separate counter for the old and new indices because we will have to increment them differently once we start to have holes.

$new_data = array();
$j = 0;
for($i = 0; $i < $total; $i++) {
  $old_x = floor($i / $width); // integer division
  $old_y = $i % $width;        // modulo

  do {
    $new_x = $j % $height;        // modulo
    $new_y = floor($j / $height); // integer division
    $j++;
  // move on to the next position if we have reached an index that isn't available in the old data structure
  } while (!isset($data[$new_x][$new_y]) && $j < $total);

  if (!isset($new_data[$new_x])) {
    $new_data[$new_x] = array();
  }
  if (isset($data[$old_x][$old_y])) {
    $new_data[$new_x][$new_y] = $data[$old_x][$old_y];
  }
}

Problem

Been checking out other ways used to order array values vertically for use in a table but most of them were the equivalent of flipping your table 90 deg to the right. I've been trying to think of a way to properly implement this but I think I need some help. For example, the table (horizontal order): ``` a b c d e f g h i j k l m n o p q r ``` Is reordered to (vertical order): ``` a e i m p b f j n q c g k o r d h l ``` As you can see the structure is retained since the last 2 cells are empty. Not like this: ``` a e i m q b f j n r c g k o d h l p ``` In this example, the table is akin to flipping it sideways. Does anyone know how to properly do this?

Original source

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