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<?php
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// $Id$
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/**
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* Common things in SNA related files
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*
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* Store functions, constants that almost all file needs in SNA module
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* @author Aron Novak <aaron@szentimre.hu
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* @version 0.1
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* @package sna
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*/
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/**
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* The path of data files. This path can be modify trough drupal settings.
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*/
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define('FILES_PATH', './');
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/**
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* The path to the visualization applet
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*/
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define('APPLET_PATH', 'sites/sna.drupaler.net/applet_tryout/');
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/**
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* Set the dba_handler
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*/
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define('DBA_HANDLER', 'gdbm');
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if (function_exists('variable_get')) {
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$files_path = variable_get('sna_data_path', FILES_PATH);
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$pic_size = variable_get('sna_pic_size', 300);
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}
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else {
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$files_path = FILES_PATH;
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$pic_size = 300;
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}
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/**
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* Here store the whole graph. Should be inaccessible for www user
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*/
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define('DATA_PATH', $files_path . 'ser.dat');
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//define('DATA_PATH', './ser.dat');
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/**
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* The Graphviz file's path
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*/
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define('DOT_PATH', $files_path . 'my.dot');
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/**
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* The Pajek file's path
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*/
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define('NET_PATH', $files_path . 'my.net');
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/**
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* The minimal tree of shortest route - cache
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*/
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define('CACHE_PATH', $files_path . 'min_trees');
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/**
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* Possible options: nodes, buddy, stats
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*/
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define('GRAPH_SOURCE', 'nodes');
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/**
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* At cron-time the script generate the top NUM_CACHE users minimal tree
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*/
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define('NUM_CACHE', '10');
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/**
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* SVG picture width
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*/
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define('PIC_WIDTH', $pic_size);
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/**
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* SVG picture height - same as width, we need 1:1 side proportion!
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*/
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define('PIC_HEIGHT', PIC_WIDTH);
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/**
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* Performace tester helper function. Start a timer and measure the current memory usage
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*
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* @return array Startup measured time and memory usage
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*/
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function res_start() {
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static $timer_index;
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$mem_start = function_exists("memory_get_usage") ? memory_get_usage() : 0;
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timer_start($timer_index);
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return array(&$timer_index, $mem_start);
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}
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/**
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* Performace tester helper function. Compute the diff between res_start's figures.
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*
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* @param array $at_start Startup measured time and memory usage
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*/
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function res_stop($at_start) {
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$res["time"] = timer_read($at_start[0]) / 1000 . " sec";
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$res["mem"] = function_exists("memory_get_usage") ? (memory_get_usage() - $at_start[1]) / 1024 . " kB" : "NaN";
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timer_stop($at_start[0]++);
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return $res;
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}
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/**
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* Lock the data file to avoid data corruption
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*
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* @param file_pointer $file_p
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* @return boolean success or not
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*/
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function lock($file_p) {
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while (!flock($file_p, LOCK_EX)) {
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$i++;
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usleep(10);
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if ($i > 10) {
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return FALSE;
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}
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}
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return TRUE;
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}
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/**
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* Get the nickname of a user
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*
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* @param user_id $uid Drupal uid of the user
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* @return nickname The uid's drupal nickname
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*/
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function get_real_name($uid) {
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$name_q = "SELECT name FROM users WHERE uid = %d";
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$name = db_query($name_q, $uid);
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$line = db_fetch_array($name);
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return $line["name"];
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}
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/**
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* Get from the database all the users' uid
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*
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* @return array All the users uid
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*/
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function get_all_vertices() {
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$vertices_q = "SELECT uid FROM users WHERE status = 1";
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$vertices = db_query($vertices_q);
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while ($line = db_fetch_array($vertices)) {
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$users[] = $line['uid'];
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}
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return $users;
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}
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/**
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* Get from the database all the users' uid and name to and assoc array
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*
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* @return array All the users uid and name
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*/
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function get_all_vertices_for_forms() {
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$vertices_q = "SELECT uid, name FROM users WHERE status = 1";
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$vertices = db_query($vertices_q);
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while ($line = db_fetch_array($vertices)) {
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$users[$line['uid']] = $line['name'];
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}
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return $users;
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}
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/**
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* Return the number of out-edges
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*
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* @param array $edges The adjacentcy list of the graph
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* @param integer $vertex The vertex's id
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* @return integer The number of out-edges
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*/
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function vertex_degree($edges, $vertex) {
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return count($edges[$vertex]);
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}
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/**
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* Check if the minimal tree of <var>$vertex</var> is in cache or not
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*
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* @param integer $vertex The vertex's id
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* @return boolean In cache or not
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*/
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function is_in_cache($vertex) {
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if (!$db = dba_open(CACHE_PATH, "c", DBA_HANDLER)) {
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die("Cannot open database\n");
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}
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$data = dba_fetch($vertex, $db);
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dba_close($db);
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return $data === FALSE ? FALSE : unserialize($data);
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}
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/**
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* Put the generated minimal tree to the cache
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*
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* @param integer $vertex The vertex's id
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* @param array $data The minimal routes tree of $vertex
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* @return boolean Success or not
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*/
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function put_in_cache($vertex, $data) {
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if (!$db = dba_open(CACHE_PATH, "c", DBA_HANDLER)) {
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return FALSE;
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}
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if (!dba_insert($vertex, serialize($data), $db)) {
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dba_close($db);
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return FALSE;
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}
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dba_close($db);
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return TRUE;
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}
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/**
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* Find all the shortest routes from one vertex - Dijkstra algorithm
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*
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* @param array $edges The adjacentcy list of the graph
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* @param integer $a The vertex's id
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* @return array The minimal tree of routes
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*/
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function a_to_any($edges, $a, $in_explore = false) {
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if (!$in_explore) {
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if ($data = is_in_cache($a)) {
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return $data;
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}
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}
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/* Set start values and load all the vertices in Q row */
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$Q = array();
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foreach ($edges as $key => $rel) {
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$d[$key] = '-'; // Distance from $a
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$p[$key] = '-';
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$Q[] = $key;
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foreach (array_keys($rel) as $child) {
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$d[$child] = '-'; // Distance from $a
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$p[$child] = '-';
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$Q[] = $child;
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}
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}
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/* The distance of start point is 0 */
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$d[$a] = 0;
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$Q[] = $a;
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/* Delete duplicated elements */
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$Q = array_unique($Q);
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while (count($Q)) {
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/* Search the minimal d in Q */
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$u = reset($Q);
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$min = $d[$u];
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$min_key = key($Q);
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foreach ($Q as $vk => $vertex) {
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if (($min > $d[$vertex] || $min === '-') && is_numeric($d[$vertex])) {
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$min = $d[$vertex];
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$u = $vertex;
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$min_key = $vk;
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}
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}
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unset($Q[$min_key]);
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/* Test the edges of $u vertex */
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if (isset($edges[$u]) && $d[$u] !== '-') {
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foreach (array_keys($edges[$u]) as $next) {
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/* Test if get a shorter route - relaxation */
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$w = $edges[$u][$next];
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if ($d[$next] > $d[$u] + $w || $d[$next] === '-') {
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$d[$next] = $d[$u] + $w;
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$p[$next] = $u;
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}
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}
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}
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}
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$out = array('dist' => $d, 'prev' => $p);
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put_in_cache($a, $out);
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return $out;
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}
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/**
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* This is the graph's cost function
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* In a weighted graph or digraph,
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* each edge is associated with some value,
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* variously called its cost, weight, length
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*
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* @param array $edges The adjacentcy list of the graph
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* @param integer $a From verticle
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* @param integer $b To verticle
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* @return integer The weight of the edge or FALSE if the edge is not set
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*/
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function get_edge_weight($edges, $a, $b, $min, $max) {
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if (isset($edges[$a][$b])) {
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/*
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* The function is a line. This line contains two points
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* x1 y1 x2 y2
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* P1 (min, max_length) and P2 (max, min_length)
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* min_length: 1 , max_length: 10
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* The line's equation : y - y1 = (y2 - y1) / (x2 - x1) (x - x1)
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* The result is a number between 1 and 10. 1 represents the
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* strongest connection.
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*/
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if ($max != $min) {
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$y = (- 9 / ($max - $min) * ($edges[$a][$b] - $min)) + 10;
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}
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else { // Avoid division by zero!
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$y = 1;
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}
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return $y;
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}
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else { // No edge from a to b
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return FALSE;
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}
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}
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/**
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* Search the smallest and the biggest value in the <var>$edges</var> array that
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* represents connection strength
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*
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* @param array $edges The adjacentcy list of the graph
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* @return integer The length of the edge
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*/
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function get_min_and_max_degree($edges) {
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static $cached_arr;
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$degrees = array();
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if (is_array($cached_arr)) {
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return $cached_arr;
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}
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else {
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foreach ($edges as $neighbours) {
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foreach ($neighbours as $degree) {
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$degrees[] = $degree;
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}
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}
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sort($degrees);
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$cached_arr = array(reset($degrees), end($degrees));
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return $cached_arr;
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}
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}
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/**
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* Sort the edges by the number of out-edges
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*
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* @param array $edges The adjacentcy list of the graph
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* @param integer $limit Return the <var>$limit</var> - top of the users
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* @return array The sorted vertices list
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*/
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function sort_by_popularity($edges, $limit = -1) {
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$popularity = array();
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foreach (array_keys($edges) as $vertex) {
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$popularity[] = array(vertex_degree($edges, $vertex), $vertex);
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}
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usort($popularity, "compare");
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return $limit === -1 ? $popularity : array_slice($popularity, 0, $limit);
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}
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/**
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* Special compare function to sort multi-dimensional array easily
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*
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* @param array $a
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* @param array $b
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* @return boolean $b is greater than $a
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*/
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function compare($a, $b) {
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if ($a[0] < $b[0]) {
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return TRUE;
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}
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else {
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return FALSE;
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}
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}
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/**
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* Clear the dbm file that store the cached minimal routes
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*
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*/
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function clear_cache() {
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$db = dba_open(CACHE_PATH, "n", DBA_HANDLER);
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dba_close($db);
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}
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?>
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