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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Abstract discrete indicator.
  19   *
  20   * @package   core_analytics
  21   * @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
  22   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  namespace core_analytics\local\indicator;
  26  
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  /**
  30   * Abstract discrete indicator.
  31   *
  32   * @package   core_analytics
  33   * @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
  34   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  35   */
  36  abstract class discrete extends base {
  37  
  38      /**
  39       * Classes need to be defined so they can be converted internally to individual dataset features.
  40       *
  41       * @return string[]
  42       */
  43      protected static function get_classes() {
  44          throw new \coding_exception('Please overwrite get_classes() specifying your discrete-values\' indicator classes');
  45      }
  46  
  47      /**
  48       * Returns 1 feature header for each of the classes.
  49       *
  50       * @return string[]
  51       */
  52      public static function get_feature_headers() {
  53          $fullclassname = '\\' . get_called_class();
  54  
  55          foreach (static::get_classes() as $class) {
  56              $headers[] = $fullclassname . '/' . $class;
  57          }
  58  
  59          return $headers;
  60      }
  61  
  62      /**
  63       * Whether the value should be displayed or not.
  64       *
  65       * @param float $value
  66       * @param string $subtype
  67       * @return bool
  68       */
  69      public function should_be_displayed($value, $subtype) {
  70          if ($value != static::get_max_value()) {
  71              // Discrete values indicators are converted internally to 1 feature per indicator, we are only interested
  72              // in showing the feature flagged with the max value.
  73              return false;
  74          }
  75          return true;
  76      }
  77  
  78      /**
  79       * Returns the value to display when the prediction is $value.
  80       *
  81       * @param float $value
  82       * @param string $subtype
  83       * @return string
  84       */
  85      public function get_display_value($value, $subtype = false) {
  86  
  87          $displayvalue = array_search($subtype, static::get_classes(), false);
  88  
  89          debugging('Please overwrite \core_analytics\local\indicator\discrete::get_display_value to show something ' .
  90              'different than the default "' . $displayvalue . '"', DEBUG_DEVELOPER);
  91  
  92          return $displayvalue;
  93      }
  94  
  95      /**
  96       * get_display_style
  97       *
  98       * @param float $ignoredvalue
  99       * @param string $ignoredsubtype
 100       * @return int
 101       */
 102      public function get_display_style($ignoredvalue, $ignoredsubtype) {
 103          // No style attached to indicators classes, they are what they are, a cat,
 104          // a horse or a sandwich, they are not good or bad.
 105          return \core_analytics\calculable::OUTCOME_NEUTRAL;
 106      }
 107  
 108      /**
 109       * From calculated values to dataset features.
 110       *
 111       * One column for each class.
 112       *
 113       * @param float[] $calculatedvalues
 114       * @return float[]
 115       */
 116      protected function to_features($calculatedvalues) {
 117  
 118          $classes = static::get_classes();
 119  
 120          foreach ($calculatedvalues as $sampleid => $calculatedvalue) {
 121  
 122              // Using intval as it may come as a float from the db.
 123              $classindex = array_search(intval($calculatedvalue), $classes, true);
 124  
 125              if ($classindex === false && !is_null($calculatedvalue)) {
 126                  throw new \coding_exception(get_class($this) . ' calculated value "' . $calculatedvalue .
 127                      '" is not one of its defined classes (' . json_encode($classes) . ')');
 128              }
 129  
 130              // We transform the calculated value into multiple features, one for each of the possible classes.
 131              $features = array_fill(0, count($classes), 0);
 132  
 133              // 1 to the selected value.
 134              if (!is_null($calculatedvalue)) {
 135                  $features[$classindex] = 1;
 136              }
 137  
 138              $calculatedvalues[$sampleid] = $features;
 139          }
 140  
 141          return $calculatedvalues;
 142      }
 143  
 144      /**
 145       * Validates the calculated value.
 146       *
 147       * @param float $calculatedvalue
 148       * @return true
 149       */
 150      protected function validate_calculated_value($calculatedvalue) {
 151  
 152          // Using intval as it may come as a float from the db.
 153          if (!in_array(intval($calculatedvalue), static::get_classes())) {
 154              throw new \coding_exception(get_class($this) . ' calculated value "' . $calculatedvalue .
 155                  '" is not one of its defined classes (' . json_encode(static::get_classes()) . ')');
 156          }
 157          return true;
 158      }
 159  }