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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   * This script renders the quiz statistics graph.
  19   *
  20   * It takes one parameter, the quiz_statistics.id. This is enough to identify the
  21   * quiz etc.
  22   *
  23   * It plots a bar graph showing certain question statistics plotted against
  24   * question number.
  25   *
  26   * @package   quiz_statistics
  27   * @copyright 2008 Jamie Pratt
  28   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  29   */
  30  
  31  require_once(dirname(__FILE__) . '/../../../../config.php');
  32  require_once($CFG->libdir . '/graphlib.php');
  33  require_once($CFG->dirroot . '/mod/quiz/locallib.php');
  34  require_once($CFG->dirroot . '/mod/quiz/report/reportlib.php');
  35  require_once($CFG->dirroot . '/mod/quiz/report/statistics/statisticslib.php');
  36  
  37  // Get the parameters.
  38  $quizid = required_param('quizid', PARAM_INT);
  39  $currentgroup = required_param('currentgroup', PARAM_INT);
  40  $whichattempts = required_param('whichattempts', PARAM_INT);
  41  
  42  $quiz = $DB->get_record('quiz', array('id' => $quizid), '*', MUST_EXIST);
  43  $cm = get_coursemodule_from_instance('quiz', $quiz->id);
  44  
  45  // Check access.
  46  require_login($quiz->course, false, $cm);
  47  $modcontext = context_module::instance($cm->id);
  48  require_capability('quiz/statistics:view', $modcontext);
  49  
  50  if (groups_get_activity_groupmode($cm)) {
  51      $groups = groups_get_activity_allowed_groups($cm);
  52  } else {
  53      $groups = array();
  54  }
  55  if ($currentgroup && !in_array($currentgroup, array_keys($groups))) {
  56      print_error('groupnotamember', 'group');
  57  }
  58  
  59  if (empty($currentgroup)) {
  60      $groupstudents = array();
  61  } else {
  62      $groupstudents = get_users_by_capability($modcontext, array('mod/quiz:reviewmyattempts', 'mod/quiz:attempt'),
  63                                               '', '', '', '', $currentgroup, '', false);
  64  }
  65  $qubaids = quiz_statistics_qubaids_condition($quizid, $groupstudents, $whichattempts);
  66  
  67  // Load the rest of the required data.
  68  $questions = quiz_report_get_significant_questions($quiz);
  69  
  70  // Only load main question not sub questions.
  71  $questionstatistics = $DB->get_records_select('question_statistics', 'hashcode = ? AND slot IS NOT NULL',
  72                                                array($qubaids->get_hash_code()));
  73  
  74  // Create the graph, and set the basic options.
  75  $graph = new graph(800, 600);
  76  $graph->parameter['title']   = '';
  77  
  78  $graph->parameter['y_label_left'] = '%';
  79  $graph->parameter['x_label'] = get_string('position', 'quiz_statistics');
  80  $graph->parameter['y_label_angle'] = 90;
  81  $graph->parameter['x_label_angle'] = 0;
  82  $graph->parameter['x_axis_angle'] = 60;
  83  
  84  $graph->parameter['legend'] = 'outside-right';
  85  $graph->parameter['legend_border'] = 'black';
  86  $graph->parameter['legend_offset'] = 4;
  87  
  88  $graph->parameter['bar_size'] = 1;
  89  
  90  $graph->parameter['zero_axis'] = 'grayEE';
  91  
  92  // Configure what to display.
  93  $fieldstoplot = array(
  94      'facility' => get_string('facility', 'quiz_statistics'),
  95      'discriminativeefficiency' => get_string('discriminative_efficiency', 'quiz_statistics')
  96  );
  97  $fieldstoplotfactor = array('facility' => 100, 'discriminativeefficiency' => 1);
  98  
  99  // Prepare the arrays to hold the data.
 100  $xdata = array();
 101  foreach (array_keys($fieldstoplot) as $fieldtoplot) {
 102      $ydata[$fieldtoplot] = array();
 103      $graph->y_format[$fieldtoplot] = array(
 104          'colour' => quiz_statistics_graph_get_new_colour(),
 105          'bar' => 'fill',
 106          'shadow_offset' => 1,
 107          'legend' => $fieldstoplot[$fieldtoplot]
 108      );
 109  }
 110  
 111  // Fill in the data for each question.
 112  foreach ($questionstatistics as $questionstatistic) {
 113      $number = $questions[$questionstatistic->slot]->number;
 114      $xdata[$number] = $number;
 115  
 116      foreach ($fieldstoplot as $fieldtoplot => $notused) {
 117          $value = $questionstatistic->$fieldtoplot;
 118          if (is_null($value)) {
 119              $value = 0;
 120          }
 121          $value *= $fieldstoplotfactor[$fieldtoplot];
 122  
 123          $ydata[$fieldtoplot][$number] = $value;
 124      }
 125  }
 126  
 127  // Sort the fields into order.
 128  sort($xdata);
 129  $graph->x_data = array_values($xdata);
 130  
 131  foreach ($fieldstoplot as $fieldtoplot => $notused) {
 132      ksort($ydata[$fieldtoplot]);
 133      $graph->y_data[$fieldtoplot] = array_values($ydata[$fieldtoplot]);
 134  }
 135  $graph->y_order = array_keys($fieldstoplot);
 136  
 137  // Find appropriate axis limits.
 138  $max = 0;
 139  $min = 0;
 140  foreach ($fieldstoplot as $fieldtoplot => $notused) {
 141      $max = max($max, max($graph->y_data[$fieldtoplot]));
 142      $min = min($min, min($graph->y_data[$fieldtoplot]));
 143  }
 144  
 145  // Set the remaining graph options that depend on the data.
 146  $gridresolution = 10;
 147  $max = ceil($max / $gridresolution) * $gridresolution;
 148  $min = floor($min / $gridresolution) * $gridresolution;
 149  
 150  if ($max == $min) {
 151      // Make sure there is some difference between min and max y values.
 152      $max = $min + $gridresolution;
 153  }
 154  
 155  $gridlines = ceil(($max - $min) / $gridresolution) + 1;
 156  
 157  $graph->parameter['y_axis_gridlines'] = $gridlines;
 158  
 159  $graph->parameter['y_min_left'] = $min;
 160  $graph->parameter['y_max_left'] = $max;
 161  $graph->parameter['y_decimal_left'] = 0;
 162  
 163  // Output the graph.
 164  $graph->draw();