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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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 * Abstract discrete indicator.
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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\indicator;
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defined('MOODLE_INTERNAL') || die();
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/**
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 * Abstract discrete indicator.
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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 discrete extends base {
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    /**
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     * Classes need to be defined so they can be converted internally to individual dataset features.
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     *
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     * @return string[]
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     */
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    protected static function get_classes() {
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        throw new \coding_exception('Please overwrite get_classes() specifying your discrete-values\' indicator classes');
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    }
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    /**
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     * Returns 1 feature header for each of the classes.
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     *
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     * @return string[]
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     */
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    public static function get_feature_headers() {
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        $fullclassname = '\\' . get_called_class();
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        foreach (static::get_classes() as $class) {
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            $headers[] = $fullclassname . '/' . $class;
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        }
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        return $headers;
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    }
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    /**
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     * Whether the value should be displayed or not.
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     *
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     * @param float $value
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     * @param string $subtype
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     * @return bool
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     */
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    public function should_be_displayed($value, $subtype) {
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        if ($value != static::get_max_value()) {
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            // Discrete values indicators are converted internally to 1 feature per indicator, we are only interested
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            // in showing the feature flagged with the max value.
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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 value to display when the prediction is $value.
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     *
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     * @param float $value
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     * @param string $subtype
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     * @return string
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     */
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    public function get_display_value($value, $subtype = false) {
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        $displayvalue = array_search($subtype, static::get_classes(), false);
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        debugging('Please overwrite \core_analytics\local\indicator\discrete::get_display_value to show something ' .
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            'different than the default "' . $displayvalue . '"', DEBUG_DEVELOPER);
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        return $displayvalue;
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    }
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    /**
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     * get_display_style
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     *
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     * @param float $ignoredvalue
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     * @param string $ignoredsubtype
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     * @return int
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     */
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    public function get_display_style($ignoredvalue, $ignoredsubtype) {
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        // No style attached to indicators classes, they are what they are, a cat,
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        // a horse or a sandwich, they are not good or bad.
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        return \core_analytics\calculable::OUTCOME_NEUTRAL;
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    }
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    /**
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     * From calculated values to dataset features.
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     *
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     * One column for each class.
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     *
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     * @param float[] $calculatedvalues
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     * @return float[]
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     */
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    protected function to_features($calculatedvalues) {
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        $classes = static::get_classes();
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        foreach ($calculatedvalues as $sampleid => $calculatedvalue) {
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            // Using intval as it may come as a float from the db.
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            $classindex = array_search(intval($calculatedvalue), $classes, true);
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            if ($classindex === false && !is_null($calculatedvalue)) {
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                throw new \coding_exception(get_class($this) . ' calculated value "' . $calculatedvalue .
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                    '" is not one of its defined classes (' . json_encode($classes) . ')');
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            }
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            // We transform the calculated value into multiple features, one for each of the possible classes.
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            $features = array_fill(0, count($classes), 0);
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            // 1 to the selected value.
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            if (!is_null($calculatedvalue)) {
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                $features[$classindex] = 1;
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            }
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            $calculatedvalues[$sampleid] = $features;
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        }
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        return $calculatedvalues;
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    }
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    /**
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     * Validates the calculated value.
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     *
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     * @param float $calculatedvalue
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     * @return true
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     */
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    protected function validate_calculated_value($calculatedvalue) {
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        // Using intval as it may come as a float from the db.
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        if (!in_array(intval($calculatedvalue), static::get_classes())) {
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            throw new \coding_exception(get_class($this) . ' calculated value "' . $calculatedvalue .
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                '" is not one of its defined classes (' . json_encode(static::get_classes()) . ')');
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        }
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        return true;
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    }
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}