WP Filterable Portfolio

<?php
/*=======================================
* call this function to register the custom post type
=======================================*/
add_action( 'init', 'themename_custom_post_type' );
function themename_custom_post_type() {
    register_post_type( 'themename_portfolio',
        array(
            'labels' => array(
                'name' => __( 'Portfolios' ),
                'singular_name' => __( 'Portfolio' ),
                'add_new' => __( 'Add New' ),
                'add_new_item' => __( 'Add New Portfolio' ),
                'edit_item' => __( 'Edit Portfolio' ),
                'new_item' => __( 'New Portfolio' ),
                'view_item' => __( 'View Portfolio' ),
                'search_items' => __( 'Search Portfolio' ),
                'not_found' => __( 'No Portfolio found' ),
                'not_found_in_trash' => __( 'No Portfolio found in Trash' )
            ),
        'public' => true,
        'has_archive' => true,
        'exclude_from_search' => true,
        'show_ui' => true,
        'show_in_admin_bar' => true,
        'menu_position' => 5,
        'menu_icon' => 'dashicons-images-alt2', // http://melchoyce.github.io/dashicons/
        'capability_type' => 'page',
        'hierarchical' => false,
        'rewrite' => array( 'slug' => 'slide' ),
        'supports' => array( 'title','editor','thumbnail'),
        )
    );
}

/*=======================================
* call this function to register the custom taxonomy
=======================================*/
function themename_custom_taxonomy() {
    register_taxonomy(
    'portfolio_cat',
    'themename_portfolio',
    array(
        'hierarchical'          => true,
        'label'                         => 'Portfolio Categories',
        'query_var'             => true,
        'rewrite'                       => array(
            'slug'                  => 'portfolio-category',
            )
        )
    );
}
add_action( 'init', 'themename_custom_taxonomy' );

/*=======================================================
*To enable  Featured Image (Post Thumbnails) support for Custom post
=======================================================*/
add_theme_support( 'post-thumbnails', array( 'themename_portfolio' ) );
add_image_size( 'portfolio-thumb', 370, 240 );
add_image_size( 'portfolio-large', 740, 480 );
?>

<!--
/*======================================================
*Creating the Portfolio Filter
*Displaying the Portfolio Items
=======================================================*/
-->

<div class="portfolio_filter">
<?php
        $terms = get_terms("portfolio_cat");    //To get custom taxonomy catagory name
        $count = count($terms);
        echo '<ul>';
        echo '<li class="filter" data-filter="all">All</li>';
            if ( $count > 0 )
            {
                foreach ( $terms as $term ) {
                    $termname = strtolower($term->name);
                    $termname = str_replace(' ', '-', $termname);
                    echo '<li class="filter" data-filter="'.$termname.'">'.$term->name.'</li>';
                }
            }
    echo "</ul>";
?>
</div>
<div class="portfolio_content">
           <ul id="Grid"  class="gallery">
        <?php
                $loop = new WP_Query(array('post_type' => 'themename_portfolio', 'posts_per_page' => -1));
                $count =0;
        ?>
                <?php if ( $loop ) :

                while ( $loop->have_posts() ) : $loop->the_post(); ?>

                    <?php
                    $terms = get_the_terms( $post->ID, 'portfolio_cat' );   //To get custom taxonomy catagory name

                    if ( $terms && ! is_wp_error( $terms ) ) :
                            $links = array();

                            foreach ( $terms as $term )
                            {
                                $links[] = $term->name;
                            }
                            $links = str_replace(' ', '-', $links);
                            $tax = join( " ", $links );
                    else :
                            $tax = '';
                    endif;
                    ?>

                    <li class="mix all <?php echo strtolower($tax); ?>">
                                    <div class="single_portfolio">
                                      <?php the_post_thumbnail('portfolio-thumb'); ?>
                <div class="mask">
                    <?php $portfolio_large = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'portfolio-large' ); ?>
                    <a href="<?php echo $portfolio_large[0]; ?>" rel="prettyPhoto" title="This is the description"><i class=" search_icon fa fa-search"></i></a>
                    <a href="<?php the_permalink();?>"><i class=" picture_icon fa fa-picture-o"></i></a>
                </div>
            </div>
                       </li>

                <?php endwhile; else: ?>

                    <li class="error-not-found">Sorry, no portfolio entries found.</li>

                <?php endif; ?>
            </ul>
</div>