Files
moodle/analytics/classes/local/indicator/discrete.php
T
David Monllao 5c5cb3ee15 MDL-59265 analytics: Rename machine learning backend method
- Method names renamed to avoid interface changes once
  we support regression and unsupervised learning
- Adding regressor interface even if not implemente
- predictor interface comments expanded
- Differentiate model's required accuracy from predictions quality
- Add missing get_callback_boundary call
- Updated datasets' metadata to allow 3rd parties to code
  regressors themselves
- Add missing option to exception message
- Include target data into the dataset regardless of being a prediction
  dataset or a training dataset
- Explicit in_array and array_search non-strict calls
- Overwrite discrete should_be_displayed implementation with the binary one
- Overwrite no_teacher get_display_value as it would otherwise look
  wrong
- Other minor fixes
2017-08-25 13:17:22 +02:00

142 lines
4.4 KiB
PHP

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