Order posts by year and month

posts-by-month.php

<?php

/**
 * Get Posts by Year
 *
 * Returns an array of posts
 * sorted by year and month.
 *
 * @param string $post_type Post Type
 * @param array $options Options array for get_posts()
 */
function get_posts_by_year( $post_type = 'post', $options = array() ) {

    // Set Default options
    $defaults = array(
        'post_type' => $post_type,
        'posts_per_page' => -1,
        'orderby' => 'post_date',
        'order' => 'DESC'
    );
    
    // Merge options with defaults
    $options = array_merge($defaults, $options);

    // Get posts
    $the_posts = get_posts($options);

    // False if no posts
    if ( !$the_posts )
        return false;
    
    // Sort posts
    foreach ( $the_posts as $p ) {
        $timestamp = strtotime($p->post_date);
        $year = date('Y', $timestamp);
        $month = date('n', $timestamp);

        $sorted[$year][$month][] = $p;
    }
    
    // Done!
    return $sorted;
  
}