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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/>.
/**
* Discrete values target.
*
* @package core_analytics
* @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_analytics\local\target;
defined('MOODLE_INTERNAL') || die();
/**
* Discrete values target.
*
* @package core_analytics
* @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class discrete extends base {
/**
* Are this target calculations linear values?
*
* @return bool
*/
public function is_linear() {
// Not supported yet.
throw new \coding_exception('Sorry, this version\'s prediction processors only support targets with binary values.' .
' You can write your own and overwrite this method though.');
}
/**
* Is the provided class one of this target valid classes?
*
* @param mixed $class
* @return bool
*/
protected static function is_a_class($class) {
return (in_array($class, static::get_classes(), false));
}
/**
* get_display_value
*
* @param float $value
* @param string $ignoredsubtype
* @return string
*/
public function get_display_value($value, $ignoredsubtype = false) {
if (!self::is_a_class($value)) {
throw new \moodle_exception('errorpredictionformat', 'analytics');
}
// To discard any possible weird keys devs used.
$classes = array_values(static::get_classes());
$descriptions = array_values(static::classes_description());
if (count($classes) !== count($descriptions)) {
throw new \coding_exception('You need to describe all your classes (' . json_encode($classes) .
') in self::classes_description');
}
$key = array_search($value, $classes);
if ($key === false) {
throw new \coding_exception('You need to describe all your classes (' . json_encode($classes) .
') in self::classes_description');
}
return $descriptions[$key];
}
/**
* get_calculation_outcome
*
* @param float $value
* @param string $ignoredsubtype
* @return int
*/
public function get_calculation_outcome($value, $ignoredsubtype = false) {
if (!self::is_a_class($value)) {
throw new \moodle_exception('errorpredictionformat', 'analytics');
}
if (in_array($value, $this->ignored_predicted_classes(), false)) {
// Just in case, if it is ignored the prediction should not even be recorded.
return self::OUTCOME_OK;
}
debugging('Please overwrite \core_analytics\local\target\discrete::get_calculation_outcome, all your target ' .
'classes are styled the same way otherwise', DEBUG_DEVELOPER);
return self::OUTCOME_OK;
}
/**
* Returns all the possible values the target calculation can return.
*
* Only useful for targets using discrete values, must be overwriten if it is the case.
*
* @return array
*/
public static function get_classes() {
// Coding exception as this will only be called if this target have non-linear values.
throw new \coding_exception('Overwrite get_classes() and return an array with the different values the ' .
'target calculation can return');
}
/**
* Returns descriptions for each of the values the target calculation can return.
*
* The array indexes should match self::get_classes indexes.
*
* @return array
*/
protected static function classes_description() {
throw new \coding_exception('Overwrite classes_description() and return an array with a description for each of the ' .
'different values the target calculation can return. Indexes should match self::get_classes indexes');
}
/**
* Returns the predicted classes that will be ignored.
*
* Better be keen to add more than less classes here, the callback is always able to discard some classes. As an example
* a target with classes 'grade 0-3', 'grade 3-6', 'grade 6-8' and 'grade 8-10' is interested in flagging both 'grade 6-8'
* and 'grade 8-10' as ignored. On the other hand, a target like dropout risk with classes 'yes', 'no' may just be
* interested in 'yes'.
*
* @return array List of values that will be ignored (array keys are ignored).
*/
public function ignored_predicted_classes() {
// Coding exception as this will only be called if this target have non-linear values.
throw new \coding_exception('Overwrite ignored_predicted_classes() and return an array with the classes that should not ' .
'trigger the callback');
}
/**
* This method determines if a prediction is interesing for the model or not.
*
* This method internally calls ignored_predicted_classes to skip classes
* flagged by the target as not important for users.
*
* @param mixed $predictedvalue
* @param float $predictionscore
* @return bool
*/
public function triggers_callback($predictedvalue, $predictionscore) {
if (!parent::triggers_callback($predictedvalue, $predictionscore)) {
return false;
}
if (in_array($predictedvalue, $this->ignored_predicted_classes())) {
return false;
}
return true;
}
}