/**
* Given the data of the historic users and the current ones, creates a matrix of association coefficients, with the
* current users as rows, and the historic user as columns.
*
* @see cosine_similarity($vector1, $vector2).
* @param array $currentdata A 2D array.
* @param array $historicdata A 2D array.
* @param \text_progress_trace $trace Text output trace.
* @return array The association matrix; empty if no association could be made.
*/
public function create_associations_matrix($currentdata, $historicdata, $trace)
{
$db = new database_helper();
$trace->output("[mycourse " . date('d/m/Y H:i:s') . "]: Starting creation of associations matrix.");
$trace->output("[mycourse " . date('d/m/Y H:i:s') . "]: Transforming receiving data to get a matrix of users x resources. " . " with the views as values.");
$currenttransformeddata = $this->matrix->transform_queried_data($currentdata);
$historictransformeddata = $this->matrix->transform_queried_data($historicdata);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Both historic and current data have been transformed.');
$currentusers = array_keys($currenttransformeddata);
$historicusers = array_keys($historictransformeddata);
$matrix = array();
foreach ($currentusers as $currentuser) {
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . "]: Starting calculating associations for current user " . "{$currentuser}.");
$currentviewsvector = $currenttransformeddata[$currentuser];
$similarities = null;
foreach ($historicusers as $historicuser) {
$historicviewsvector = $historictransformeddata[$historicuser];
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . "]: Starting calculating cosine similarity between a vector " . "of " . count($currentviewsvector) . " elements with a vector of " . count($historicviewsvector) . " elements.");
$similarity = $this->cosine_similarity($currentviewsvector, $historicviewsvector);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Cosine similarity between those vectors has been ' . 'calculated.');
$similarity = round($similarity, 4);
$similarities[$historicuser] = $similarity;
$db->insert_similarity($currentuser, $historicuser, $similarity, $this->currentweek);
}
$matrix[$currentuser] = $similarities;
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . "]: Similarities for current user {$currentuser} have been " . "calculated.");
}
return $matrix;
}
/**
* Creates the instances of the components to use to calculate the recommendations.
*
* @param \text_progress_trace $trace Text output trace.
*/
protected function initialize($trace)
{
$this->db = new database_helper();
$this->matrix = new decimal_matrix();
$this->associator = new cosine_similarity_associator($this->matrix);
$this->recommendator = new simple_recommendator($this->associator);
$trace->output('[mycourse]: Components initializated.');
}
public function test_text_progres_trace()
{
$this->resetAfterTest(false);
$trace = new text_progress_trace();
$trace->output('do');
$trace->output('re', 1);
$trace->output('mi', 2);
$trace->finished();
$this->expectOutputString("do\n re\n mi\n");
}
/**
* Creates the associations between the current users and historic users. In this simple_recommendator implementation,
* each current user is associated with a UNIQUE previous user.
* If $currentweek is the week of the year after the course start, we have to add 52 to $currentweek, otherwise, the
* query won't return results, because $currentweek will be lower than the start week.
*
* @see get_selected_users($courseid) in database_helper.php.
* @see get_course_start_week_and_year($courseid) in database_helper.php.
* @see query_data($courseid, $year, $startweek, $currentweek) in database_helper.php.
* @see find_course_previous_teachings_ids($courseid, $year) in database_helper.php.
* @see create_associations_matrix in abstract_associator.php.
* @see insert_associations in database_helper.php.
* @param int $courseid The current course id.
* @param int $currentweek The current week of the current course.
* @param \text_progress_trace $trace Text output trace.
* @return boolean False if no association could be done; true if yes.
*/
public function create_associations($courseid, $currentweek, $trace = null)
{
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Creating associations.');
$selectedusers = $this->db->get_selected_users($courseid);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Selected users to receive recommendations:');
foreach ($selectedusers as $selecteduser) {
$trace->output("[mycourse]: \t- {$selecteduser}");
}
$coursedates = $this->db->get_course_start_week_and_year($courseid, false);
$currentstartweek = $coursedates['week'];
$currentyear = $coursedates['year'];
$trace->output("[mycourse " . date('d/m/Y H:i:s') . "]: Course start year: {$currentyear}; start week: {$currentstartweek}");
$yearchange = $currentstartweek > $currentweek;
$endweek = $currentweek;
if ($yearchange) {
$endweek = $currentweek + 52;
}
$endweek += parent::TIME_WINDOW;
$previouscourses = $this->db->get_associated_courses($courseid);
$previouscourse = max($previouscourses);
$trace->output("[mycourse " . date('d/m/Y H:i:s') . "]: Current course: '{$courseid}' will use the historic course " . "'{$previouscourse}' for the associations.");
$coursedates = $this->db->get_course_start_week_and_year($previouscourse, true);
$startweek = $coursedates['week'];
$year = $coursedates['year'];
$previousresources = $this->db->query_historic_resources_info($previouscourse);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Starting the association of common resources in both ' . 'years, to determine which resources of previous year correspond to current\'s, to decide which can be candidate ' . 'to be recommended.');
$currentresources = $this->db->query_current_resources_info($courseid);
$associatedresources = $this->associate_resources($previousresources, $currentresources);
$previousresources = $associatedresources['previous'];
$currentresources = $associatedresources['current'];
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Resource association ended.');
$onlyrecommendable = true;
$previousdata = $this->db->query_historic_course_data($previouscourse, $year, $startweek, $endweek, null, true, $onlyrecommendable, $previousresources);
$trace->output("[mycourse " . date('d/m/Y H:i:s') . "]: Log data for course '{$courseid}' will be queried with the " . "followingparameters: year: {$year}; from start week: {$startweek}; to end week: {$endweek}");
$currentdata = $this->db->query_data($courseid, $currentyear, $currentstartweek, $endweek, null, false, false, $onlyrecommendable, $currentresources);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Previous query has finished.');
// We keep only the users that are selected to receive the recommendations.
$currentselecteddata = array();
foreach ($currentdata as $currentuserrow) {
$isselecteduser = in_array($currentuserrow->get_userid(), $selectedusers);
if ($isselecteduser) {
array_push($currentselecteddata, $currentuserrow);
}
}
// We get the association matrix, where the rows will be the current users id; the columns, the previous users;
// and the values, the simmilarity coefficient.
$this->associator->set_currentweek($currentweek);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Starting association matrix creation, where each current user ' . ' will be associated with the most similar previous user.');
$associationmatrix = $this->associator->create_associations_matrix($currentselecteddata, $previousdata, $trace);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Association matrix creation ended.');
if (!empty($associationmatrix)) {
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Associations between current and historic users were made ' . 'successfully.');
$number = count($associationmatrix);
$currentusersids = array();
$historicusersids = array();
// We have to find the highest coefficient of the relation of each current user with each previous student.
foreach ($associationmatrix as $currentuser => $similarities) {
$highestsimilarityindex = array_keys($similarities, max($similarities));
$associatedhistoric = $similarities[$highestsimilarityindex[0]];
array_push($currentusersids, $currentuser);
// The key, user id, of the highest similarity coefficient, will be the most similar user.
array_push($historicusersids, intval($highestsimilarityindex[0]));
$trace->output("[mycourse]: Current user '{$currentuser}' has been associated with historic user" . " '{$highestsimilarityindex['0']}'.");
}
// Finally, we call the function that will insert the associations into the database.
$this->db->insert_associations($number, $currentusersids, $courseid, $historicusersids, $previouscourse, $currentweek);
$trace->output('[mycourse ' . date('d/m/Y H:i:s') . ']: Users associations have been inserted into database.');
return true;
} else {
$trace->output("[mycourse " . date('d/m/Y H:i:s') . "]: No associations could be done because the current course " . "'{$courseid}' and the historic course '{$previouscourse}' do not share any resources.");
return false;
}
}
