Using Facebook's Social Graph to Find A WordPress Blog's Most Popular Posts

popularposts.php

<?php

	// this goes into your theme's functions.php file

	function popularPosts($limit) {
		global $wpdb;
		$posts = $wpdb->get_results("SELECT * FROM wp_posts WHERE $wpdb->posts.post_status='publish' AND $wpdb->posts.post_type='post'");
		// get data for each post
		$popular = array();
		foreach ($posts as $post) {
			setup_postdata($post);
			$info = array();
			$info["id"] = $post->ID;
			$info["title"] = $post->post_title;
			$info["url"] = get_permalink($info["id"]);
			$info["excerpt"] = $post->post_excerpt;
			$info["shares"] = json_decode(file_get_contents("http://graph.facebook.com/".$info["url"]))->{"shares"};
			$popular[$info["shares"]] = $info;
		}
		// sort posts by number of shares
		function sortByOneKey(array $array, $key, $asc = true) {
		    $result = array();
		    $values = array();
		    foreach ($array as $id => $value) {
		        $values[$id] = isset($value[$key]) ? $value[$key] : '';
		    }
		    if ($asc) {
		        asort($values);
		    } else {
		        arsort($values);
		    }
		    foreach ($values as $key => $value) {
		        $result[$key] = $array[$key];
		    }
		    return $result;
		}
		$popular = sortByOneKey($popular, "shares", false);
		// prepare a list of the most popular posts
		$i = 0;
		foreach ($popular as $post) {
			if(++$i > $limit) break;
			echo '<div class="excerpt"><a href="'.$post["url"].'">'.$post["title"].'</a>: '.$post["excerpt"].'</div>'; // modify this to suit your theme's needs
		}
	}	

?>

<?php

	// this goes into your theme wherever you want the list of popular posts to go, change the number to modify how many posts are shown

	echo popularPosts(5)

?>