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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Drop out course target.
*
* @package core_course
* @copyright 2016 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_course\analytics\target;
defined('MOODLE_INTERNAL') || die();
require_once($CFG->dirroot . '/course/lib.php');
require_once($CFG->dirroot . '/lib/gradelib.php');
require_once($CFG->dirroot . '/lib/completionlib.php');
require_once($CFG->dirroot . '/completion/completion_completion.php');
/**
* Drop out course target.
*
* @package core_course
* @copyright 2016 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class course_dropout extends course_enrolments {
/**
* Returns the name.
*
* If there is a corresponding '_help' string this will be shown as well.
*
* @return \lang_string
*/
public static function get_name() : \lang_string {
return new \lang_string('target:coursedropout', 'course');
}
/**
* classes_description
*
* @return string[]
*/
protected static function classes_description() {
return array(
get_string('targetlabelstudentdropoutno', 'course'),
get_string('targetlabelstudentdropoutyes', 'course')
);
}
/**
* Discards courses that are not yet ready to be used for training or prediction.
*
* @param \core_analytics\analysable $course
* @param bool $fortraining
* @return true|string
*/
public function is_valid_analysable(\core_analytics\analysable $course, $fortraining = true) {
global $DB;
$isvalid = parent::is_valid_analysable($course, $fortraining);
if (is_string($isvalid)) {
return $isvalid;
}
if ($fortraining) {
// Not a valid target for training if there are not enough course accesses between the course start and end dates.
$params = array('courseid' => $course->get_id(), 'anonymous' => 0, 'start' => $course->get_start(),
'end' => $course->get_end());
list($studentssql, $studentparams) = $DB->get_in_or_equal($this->students, SQL_PARAMS_NAMED);
// Using anonymous to use the db index, not filtering by timecreated to speed it up.
$select = 'courseid = :courseid AND anonymous = :anonymous AND timecreated > :start AND timecreated < :end ' .
'AND userid ' . $studentssql;
if (!$logstore = \core_analytics\manager::get_analytics_logstore()) {
throw new \coding_exception('No available log stores');
}
$nlogs = $logstore->get_events_select_count($select, array_merge($params, $studentparams));
// At least a minimum of students activity.
$nstudents = count($this->students);
if ($nlogs / $nstudents < 10) {
return get_string('nocourseactivity', 'course');
}
}
return true;
}
/**
* calculate_sample
*
* The meaning of a drop out changes depending on the settings enabled in the course. Following these priorities order:
* 1.- Course completion
* 2.- No logs during the last quarter of the course
*
* @param int $sampleid
* @param \core_analytics\analysable $course
* @param int $starttime
* @param int $endtime
* @return float|null 0 -> not at risk, 1 -> at risk
*/
protected function calculate_sample($sampleid, \core_analytics\analysable $course, $starttime = false, $endtime = false) {
if (!$this->enrolment_active_during_analysis_time($sampleid, $starttime, $endtime)) {
// We should not use this sample as the analysis results could be misleading.
return null;
}
$userenrol = $this->retrieve('user_enrolments', $sampleid);
// We use completion as a success metric only when it is enabled.
$completion = new \completion_info($course->get_course_data());
if ($completion->is_enabled() && $completion->has_criteria()) {
$ccompletion = new \completion_completion(array('userid' => $userenrol->userid, 'course' => $course->get_id()));
if ($ccompletion->is_complete()) {
return 0;
} else {
return 1;
}
}
if (!$logstore = \core_analytics\manager::get_analytics_logstore()) {
throw new \coding_exception('No available log stores');
}
// No logs during the last quarter of the course.
$courseduration = $course->get_end() - $course->get_start();
$limit = intval($course->get_end() - ($courseduration / 4));
$select = "courseid = :courseid AND userid = :userid AND timecreated > :limit";
$params = array('userid' => $userenrol->userid, 'courseid' => $course->get_id(), 'limit' => $limit);
$nlogs = $logstore->get_events_select_count($select, $params);
if ($nlogs == 0) {
return 1;
}
return 0;
}
}