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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* Linear values target.
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*
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* @package core_analytics
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* @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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namespace core_analytics\local\target;
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defined('MOODLE_INTERNAL') || die();
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/**
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* Linear values target.
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*
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* @package core_analytics
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* @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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abstract class linear extends base {
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/**
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* Are the calculated values this target returns linear values?
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*
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* @return bool
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*/
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public function is_linear() {
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// Not supported yet.
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throw new \coding_exception('Sorry, this version\'s prediction processors only support targets with binary values.' .
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' You can write your own and overwrite this method though.');
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}
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/**
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* How positive is this calculated value?
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*
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* @param float $value
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* @param string $ignoredsubtype
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* @return int
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*/
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public function get_calculation_outcome($value, $ignoredsubtype = false) {
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// This is very generic, targets will probably be interested in overwriting this.
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$diff = static::get_max_value() - static::get_min_value();
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if (($value - static::get_min_value()) / $diff >= 0.5) {
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return self::OUTCOME_VERY_POSITIVE;
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}
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return self::OUTCOME_VERY_NEGATIVE;
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}
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/**
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* Gets the maximum value for this target
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*
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* @return float
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*/
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public static function get_max_value() {
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// Coding exception as this will only be called if this target have linear values.
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throw new \coding_exception('Overwrite get_max_value() and return the target max value');
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}
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/**
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* Gets the minimum value for this target
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*
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* @return float
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*/
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public static function get_min_value() {
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// Coding exception as this will only be called if this target have linear values.
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throw new \coding_exception('Overwrite get_min_value() and return the target min value');
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}
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/**
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* This method determines if a prediction is interesing for the model or not.
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*
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* @param mixed $predictedvalue
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* @param float $predictionscore
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* @return bool
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*/
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public function triggers_callback($predictedvalue, $predictionscore) {
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if (!parent::triggers_callback($predictedvalue, $predictionscore)) {
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return false;
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}
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// People may not want to set a boundary.
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$boundary = $this->get_callback_boundary();
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if (!empty($boundary) && floatval($predictedvalue) < $boundary) {
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return false;
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}
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return true;
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}
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/**
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* Returns the minimum value that triggers the callback.
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*
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* @return float
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*/
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protected function get_callback_boundary() {
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// Coding exception as this will only be called if this target have linear values.
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throw new \coding_exception('Overwrite get_callback_boundary() and return the min value that ' .
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'should trigger the callback');
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}
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}
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