Display Popular Posts

/*
 * Display Popular Posts
 */

function wpb_set_post_views($postID) {
    $count_key = 'wpb_post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if ($count == '') {
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    } else {
        $count++;
        update_post_meta($postID, $count_key, $count);
    }
}

//To keep the count accurate, lets get rid of prefetching
remove_action('wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0);

function wpb_track_post_views($post_id) {
    if (!is_single())
        return;
    if (empty($post_id)) {
        global $post;
        $post_id = $post->ID;
    }
    wpb_set_post_views($post_id);
}

add_action('wp_head', 'wpb_track_post_views');

function wpb_get_post_views($postID) {
    $count_key = 'wpb_post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if ($count == '') {
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
        return "0 View";
    }
    return $count . ' Views';
}

//Add shortcode for display posts
add_shortcode('ct-popular', 'ct_popular');

function ct_popular() {
    ob_start();
    $popularpost = new WP_Query(array('posts_per_page' => 4, 'meta_key' => 'wpb_post_views_count', 'orderby' => 'meta_value_num', 'order' => 'DESC'));
    while ($popularpost->have_posts()) : $popularpost->the_post();
        the_title();
    endwhile;
    wp_reset_postdata();
    return ob_get_clean();
}