Using Custom Taxonomies for Isotope Controls in MP Stacks + PostGrid:

mp-stacks-postgrid-custom-taxonomies.php

function my_custom_postgrid_isotope_taxonomies( $isotope_filter_groups ){
	
	//This array can contain custom groups (for outside sources like instgram), AND/OR WordPress taxonomy slugs.			
	$isotope_filter_groups = array( 
		'taxonomy1_slug' => array( 
			'is_wordpress_taxonomy' => true,
			'filter_group_name' => __( 'Name of Taxonomy1', 'mp_stacks_postgrid' ),
			'meta_field_ids_representing_tax_term' => array(), //Leave this blank if it is a WordPress taxonomy (as opposed to a "fake" one like "twitter-user")
			//Icon info
			'default_icon_font_string' => 'fa-th-large', //A default icon-font class string to use if no unique icon is given
			'default_icon_image_url' => plugins_url( '/assets/images/user-icon.png', dirname( dirname( __FILE__ ) ) ), //A default url to use if no unique icon is given
		),
		'taxonomy2_slug' => array( 
			'is_wordpress_taxonomy' => true,
			'filter_group_name' => __( 'Name of Taxonomy2', 'mp_stacks_postgrid' ),
			'meta_field_ids_representing_tax_term' => array(), //Leave this blank if it is a WordPress taxonomy (as opposed to a "fake" one like "twitter-user")
			//Icon info
			'default_icon_font_string' => 'fa-th-large', //A default icon-font class string to use if no unique icon is given
			'default_icon_image_url' => plugins_url( '/assets/images/user-icon.png', dirname( dirname( __FILE__ ) ) ), //A default url to use if no unique icon is given
		),
		'category' => array( 
			'is_wordpress_taxonomy' => true,
			'filter_group_name' => __( 'Categories', 'mp_stacks_postgrid' ),
			'meta_field_ids_representing_tax_term' => array(), //Leave this blank if it is a WordPress taxonomy (as opposed to a "fake" one like "twitter-user")
			//Icon info
			'default_icon_font_string' => 'fa-th-large', //A default icon-font class string to use if no unique icon is given
			'default_icon_image_url' => plugins_url( '/assets/images/user-icon.png', dirname( dirname( __FILE__ ) ) ), //A default url to use if no unique icon is given
		),
        	'post_tag' => array( 
			'is_wordpress_taxonomy' => true,
			'filter_group_name' => __( 'Post Tags', 'mp_stacks_postgrid' ),
			'meta_field_ids_representing_tax_term' => array(), //Leave this blank if it is a WordPress taxonomy (as opposed to a "fake" one like "twitter-user")
			//Icon info
			'default_icon_font_string' => 'fa-th-large', //A default icon-font class string to use if no unique icon is given
			'default_icon_image_url' => plugins_url( '/assets/images/user-icon.png', dirname( dirname( __FILE__ ) ) ), //A default url to use if no unique icon is given
		),
 	); 
    
	return $isotope_filter_groups; 
} 
add_filter( 'mp_stacks_postgrid_isotope_filter_groups', 'my_custom_postgrid_isotope_taxonomies' );