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Differences Between: [Versions 311 and 400] [Versions 311 and 401] [Versions 311 and 402] [Versions 311 and 403]

   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 file contains the code to analyse all the responses to a particular question.
  19   *
  20   * @package    core_question
  21   * @copyright  2014 Open University
  22   * @author     Jamie Pratt <me@jamiep.org>
  23   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24   */
  25  
  26  namespace core_question\statistics\responses;
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  /**
  30   * This class can compute, store and cache the analysis of the responses to a particular question.
  31   *
  32   * @package    core_question
  33   * @copyright  2014 The Open University
  34   * @author     James Pratt me@jamiep.org
  35   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  36   */
  37  class analyser {
  38      /**
  39       * @var int When analysing responses and breaking down the count of responses per try, how many columns should we break down
  40       * tries into? This is set to 5 columns, any response in a try more than try 5 will be counted in the fifth column.
  41       */
  42      const MAX_TRY_COUNTED = 5;
  43  
  44      /** @var int Time after which responses are automatically reanalysed. */
  45      const TIME_TO_CACHE = 900; // 15 minutes.
  46  
  47      /** @var object full question data from db. */
  48      protected $questiondata;
  49  
  50      /**
  51       * @var analysis_for_question|analysis_for_question_all_tries
  52       */
  53      public $analysis;
  54  
  55      /**
  56       * @var array Two index array first index is unique string for each sub question part, the second string index is the 'class'
  57       * that sub-question part can be classified into.
  58       *
  59       * This is the return value from {@link \question_type::get_possible_responses()} see that method for fuller documentation.
  60       */
  61      public $responseclasses = array();
  62  
  63      /**
  64       * @var bool whether to break down response analysis by variant. This only applies to questions that have variants and is
  65       *           used to suppress the break down of analysis by variant when there are going to be very many variants.
  66       */
  67      protected $breakdownbyvariant;
  68  
  69      /**
  70       * Create a new instance of this class for holding/computing the statistics
  71       * for a particular question.
  72       *
  73       * @param object $questiondata the full question data from the database defining this question.
  74       * @param string $whichtries   which tries to analyse.
  75       */
  76      public function __construct($questiondata, $whichtries = \question_attempt::LAST_TRY) {
  77          $this->questiondata = $questiondata;
  78          $qtypeobj = \question_bank::get_qtype($this->questiondata->qtype);
  79          if ($whichtries != \question_attempt::ALL_TRIES) {
  80              $this->analysis = new analysis_for_question($qtypeobj->get_possible_responses($this->questiondata));
  81          } else {
  82              $this->analysis = new analysis_for_question_all_tries($qtypeobj->get_possible_responses($this->questiondata));
  83          }
  84  
  85          $this->breakdownbyvariant = $qtypeobj->break_down_stats_and_response_analysis_by_variant($this->questiondata);
  86      }
  87  
  88      /**
  89       * Does the computed analysis have sub parts?
  90       *
  91       * @return bool whether this analysis has more than one subpart.
  92       */
  93      public function has_subparts() {
  94          return count($this->responseclasses) > 1;
  95      }
  96  
  97      /**
  98       * Does the computed analysis's sub parts have classes?
  99       *
 100       * @return bool whether this analysis has (a subpart with) more than one response class.
 101       */
 102      public function has_response_classes() {
 103          foreach ($this->responseclasses as $partclasses) {
 104              if (count($partclasses) > 1) {
 105                  return true;
 106              }
 107          }
 108          return false;
 109      }
 110  
 111      /**
 112       * Analyse all the response data for for all the specified attempts at this question.
 113       *
 114       * @param \qubaid_condition $qubaids which attempts to consider.
 115       * @param string $whichtries         which tries to analyse. Will be one of
 116       *                                   \question_attempt::FIRST_TRY, LAST_TRY or ALL_TRIES.
 117       * @return analysis_for_question
 118       */
 119      public function calculate($qubaids, $whichtries = \question_attempt::LAST_TRY) {
 120          // Load data.
 121          $dm = new \question_engine_data_mapper();
 122          $questionattempts = $dm->load_attempts_at_question($this->questiondata->id, $qubaids);
 123  
 124          // Analyse it.
 125          foreach ($questionattempts as $qa) {
 126              $responseparts = $qa->classify_response($whichtries);
 127              if ($this->breakdownbyvariant) {
 128                  $this->analysis->count_response_parts($qa->get_variant(), $responseparts);
 129              } else {
 130                  $this->analysis->count_response_parts(1, $responseparts);
 131              }
 132  
 133          }
 134          $this->analysis->cache($qubaids, $whichtries, $this->questiondata->id);
 135          return $this->analysis;
 136      }
 137  
 138      /**
 139       * Retrieve the computed response analysis from the question_response_analysis table.
 140       *
 141       * @param \qubaid_condition $qubaids    load the analysis of which question usages?
 142       * @param string            $whichtries load the analysis of which tries?
 143       * @return analysis_for_question|boolean analysis or false if no cached analysis found.
 144       */
 145      public function load_cached($qubaids, $whichtries) {
 146          global $DB;
 147  
 148          $timemodified = time() - self::TIME_TO_CACHE;
 149          // Variable name 'analyses' is the plural of 'analysis'.
 150          $responseanalyses = $DB->get_records_select('question_response_analysis',
 151                                              'hashcode = ? AND whichtries = ? AND questionid = ? AND timemodified > ?',
 152                                              array($qubaids->get_hash_code(), $whichtries, $this->questiondata->id, $timemodified));
 153          if (!$responseanalyses) {
 154              return false;
 155          }
 156  
 157          $analysisids = array();
 158          foreach ($responseanalyses as $responseanalysis) {
 159              $analysisforsubpart = $this->analysis->get_analysis_for_subpart($responseanalysis->variant, $responseanalysis->subqid);
 160              $class = $analysisforsubpart->get_response_class($responseanalysis->aid);
 161              $class->add_response($responseanalysis->response, $responseanalysis->credit);
 162              $analysisids[] = $responseanalysis->id;
 163          }
 164          list($sql, $params) = $DB->get_in_or_equal($analysisids);
 165          $counts = $DB->get_records_select('question_response_count', "analysisid {$sql}", $params);
 166          foreach ($counts as $count) {
 167              $responseanalysis = $responseanalyses[$count->analysisid];
 168              $analysisforsubpart = $this->analysis->get_analysis_for_subpart($responseanalysis->variant, $responseanalysis->subqid);
 169              $class = $analysisforsubpart->get_response_class($responseanalysis->aid);
 170              $class->set_response_count($responseanalysis->response, $count->try, $count->rcount);
 171  
 172          }
 173          return $this->analysis;
 174      }
 175  
 176  
 177      /**
 178       * Find time of non-expired analysis in the database.
 179       *
 180       * @param \qubaid_condition $qubaids    check for the analysis of which question usages?
 181       * @param string            $whichtries check for the analysis of which tries?
 182       * @return integer|boolean Time of cached record that matches this qubaid_condition or false if none found.
 183       */
 184      public function get_last_analysed_time($qubaids, $whichtries) {
 185          global $DB;
 186  
 187          $timemodified = time() - self::TIME_TO_CACHE;
 188          return $DB->get_field_select('question_response_analysis', 'timemodified',
 189                                       'hashcode = ? AND whichtries = ? AND questionid = ? AND timemodified > ?',
 190                                       array($qubaids->get_hash_code(), $whichtries, $this->questiondata->id, $timemodified),
 191                                       IGNORE_MULTIPLE);
 192      }
 193  }