WordPress get the top X tags for a post, based on how many times the tag has been used

gistfile1.aw

<?php
/**
 * Helper function to get the top X tags for a post, based on how many times
 * the tag has been used overall.
 *
 * @param int $post_id
 * @param int $max_tags
 * @return boolean|array
 */
function pmc_get_top_tags( $post_id, $max_tags = 3 ) {
	$post_id = absint( $post_id );
	$max_tags = absint( $max_tags );

	// Sanity check
	if ( $post_id < 1 || $max_tags < 1 ) {
		return false;
	}

	$cache_key = 'top_tags' . '_' . $post_id . '_' . $max_tags;
	$cache_data = wp_cache_get( $cache_key );
	if ( $cache_data ) {
		return $cache_data;
	}

	$top_tags = wp_get_object_terms(
		$post_id,
		'post_tag',
		array(
			'orderby' => 'count',
			'order' => 'DESC',
		)
	);

	if ( ! $top_tags || is_wp_error( $top_tags ) ) {
		return false;
	}

	// We only want to show the top $max_tags tags by count, so
	// if there are more $max_tags limit to $max_tags. If there are
	// fewer that's OK.
	$tags_count = min( $max_tags, count($top_tags) );

	$cache_data = array();
	for ( $i = 0; $i < $tags_count; $i++ ) {
		$cache_data[] = $top_tags[$i];
	}

	wp_cache_set( $cache_key, $cache_data );

	return $cache_data;
}