Proyectos de Subversion Moodle

<?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;

    }

}