I posted this on the regular stackexchange site, but then realized that there was a wordpress specific site, so I'm reposting it here.

I am trying to create a gallery within a custom post type I have created. I would like to be able to add the images/gallery to the post through the wordpress admin editor, but then have a function pull the images, wrap them in divs, and replace the existing gallery with the new images.

I would like to do the because I would like the images to fit into a grid of different sized images. For example, image 1 would be the full width, image 2 would be half the width, image 3 quarter and so on.

I have tried two methods, one being `get_children()`

    $featuredImage = get_post_thumbnail_id( $post->ID );
    $imageArgs = array(
      'numberposts' => 5,
      'order' => 'DESC',
      'post_mime_type' => 'image',
      'post_parent' => $post->ID,
      'post_type' => 'attachment',
      'exclude' => $featuredImage
    );
    $attachments = get_children($imageArgs, ARRAY_A);
    $rekeyed_array = array_values($attachments);
    $child_image = $rekeyed_array[0];
    echo '<div class="image-large"><img src="' . $child_image['guid'] . '" class="project-image"></div>';
    $child_image = $rekeyed_array[1];
    echo '<div class="image-medium"><img src="' . $child_image['guid'] . '"></div>';
    $child_image = $rekeyed_array[2];
    echo '<div class="image-small"><img src="' . $child_image['guid'] . '"></div>';

and the other being `get_post_gallery()`

    $gallery = get_post_gallery( get_the_ID(), false );

            foreach( $gallery['src'] AS $src )
            {
                ?>
                <div class="image-large">
                <img src="<?php echo $src; ?>" alt="Gallery image" />
                </div>
                <?php
            }

I haven't made much progress with the `get_post_gallery()`, but I sorta understand that I will have to use `wp_get_attachment_url()` to get the full sized images instead of thumbnails.

Now, two questions:

 1. I'm a little confused about arrays, so how would I go about
    selecting the first image in the array and wrapping it in a div with
    class "image-large" and then the second image and wrapping it in a
    div with class "image-medium"?
 2. How do I replace the gallery/images I have added through the editor
    with the new gallery/images? Right now, I get two instances of the
    images, the original added through the editor, and the images
    obtained through the functions.

**EDIT**

I figured out question 1, I think. Read up on associative arrays and realized you can do something like `echo $gallery['src'][0];` to get the source url of each image.
Still confused about question 2, though.