group shortcode

function get_celebrities_by($atts, $content = null) {

    extract( shortcode_atts( array( 'tags' => 'None' ), $atts ) );

    $display = '';
    $args = array( 'tag_slug__and' => $tags, 'posts_per_page' => 28, 'caller_get_posts'=> 1, 'numberposts' => 1 );
    $postslist = get_posts( $args );

    if($postslist) {

        foreach($postslist as $post) {
            $display .= generate_caracters($post);
        }

    } else {
        $display .= '<p>No celebrities found.</p>';
    }


    return $display;

}

function generate_caracters($post) {

    $gen = '<article id="post-'.$post->ID.'" class="home-thumb">';
        $short_title = get_post_meta($post->ID, '_hollowverse-pa-data', true);
        $short_title = $short_title->short_title;
    $gen .= '<a href="'.get_permalink($post->ID).'" title=" '.get_post_meta(get_post_thumbnail_id( $post->ID ) , '_wp_attachment_image_alt', true).' " rel="bookmark">';
    $gen .= '<div class="margin-2px">'.get_the_post_thumbnail( $post->ID, 'thumbnail' ).'</div>';
    $gen .= '<h1>'.$short_title.'</h1></a>';
    $gen .= '</article><!-- #post-'.$post->ID.'-->';

    return $gen;

}

add_shortcode( 'group', 'get_celebrities_by' );