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<?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/>.
/**
* This file contains the code to analyse all the responses to a particular question.
*
* @package core_question
* @copyright 2014 Open University
* @author Jamie Pratt <me@jamiep.org>
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_question\statistics\responses;
defined('MOODLE_INTERNAL') || die();
/**
* This class can compute, store and cache the analysis of the responses to a particular question.
*
* @package core_question
* @copyright 2014 The Open University
* @author James Pratt me@jamiep.org
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class analyser {
/**
* @var int When analysing responses and breaking down the count of responses per try, how many columns should we break down
* tries into? This is set to 5 columns, any response in a try more than try 5 will be counted in the fifth column.
*/
const MAX_TRY_COUNTED = 5;
/** @var int Time after which responses are automatically reanalysed. */
const TIME_TO_CACHE = 900; // 15 minutes.
/** @var object full question data from db. */
protected $questiondata;
/**
* @var analysis_for_question|analysis_for_question_all_tries
*/
public $analysis;
/**
* @var array Two index array first index is unique string for each sub question part, the second string index is the 'class'
* that sub-question part can be classified into.
*
* This is the return value from {@link \question_type::get_possible_responses()} see that method for fuller documentation.
*/
public $responseclasses = array();
/**
* @var bool whether to break down response analysis by variant. This only applies to questions that have variants and is
* used to suppress the break down of analysis by variant when there are going to be very many variants.
*/
protected $breakdownbyvariant;
/**
* Create a new instance of this class for holding/computing the statistics
* for a particular question.
*
* @param object $questiondata the full question data from the database defining this question.
* @param string $whichtries which tries to analyse.
*/
public function __construct($questiondata, $whichtries = \question_attempt::LAST_TRY) {
$this->questiondata = $questiondata;
$qtypeobj = \question_bank::get_qtype($this->questiondata->qtype);
if ($whichtries != \question_attempt::ALL_TRIES) {
$this->analysis = new analysis_for_question($qtypeobj->get_possible_responses($this->questiondata));
} else {
$this->analysis = new analysis_for_question_all_tries($qtypeobj->get_possible_responses($this->questiondata));
}
$this->breakdownbyvariant = $qtypeobj->break_down_stats_and_response_analysis_by_variant($this->questiondata);
}
/**
* Does the computed analysis have sub parts?
*
* @return bool whether this analysis has more than one subpart.
*/
public function has_subparts() {
return count($this->responseclasses) > 1;
}
/**
* Does the computed analysis's sub parts have classes?
*
* @return bool whether this analysis has (a subpart with) more than one response class.
*/
public function has_response_classes() {
foreach ($this->responseclasses as $partclasses) {
if (count($partclasses) > 1) {
return true;
}
}
return false;
}
/**
* Analyse all the response data for for all the specified attempts at this question.
*
* @param \qubaid_condition $qubaids which attempts to consider.
* @param string $whichtries which tries to analyse. Will be one of
* \question_attempt::FIRST_TRY, LAST_TRY or ALL_TRIES.
* @return analysis_for_question
*/
public function calculate($qubaids, $whichtries = \question_attempt::LAST_TRY) {
// Load data.
$dm = new \question_engine_data_mapper();
$questionattempts = $dm->load_attempts_at_question($this->questiondata->id, $qubaids);
// Analyse it.
foreach ($questionattempts as $qa) {
$responseparts = $qa->classify_response($whichtries);
if ($this->breakdownbyvariant) {
$this->analysis->count_response_parts($qa->get_variant(), $responseparts);
} else {
$this->analysis->count_response_parts(1, $responseparts);
}
}
$this->analysis->cache($qubaids, $whichtries, $this->questiondata->id);
return $this->analysis;
}
/**
* Retrieve the computed response analysis from the question_response_analysis table.
*
* @param \qubaid_condition $qubaids load the analysis of which question usages?
* @param string $whichtries load the analysis of which tries?
* @return analysis_for_question|boolean analysis or false if no cached analysis found.
*/
public function load_cached($qubaids, $whichtries) {
global $DB;
$timemodified = time() - self::TIME_TO_CACHE;
// Variable name 'analyses' is the plural of 'analysis'.
$responseanalyses = $DB->get_records_select('question_response_analysis',
'hashcode = ? AND whichtries = ? AND questionid = ? AND timemodified > ?',
array($qubaids->get_hash_code(), $whichtries, $this->questiondata->id, $timemodified));
if (!$responseanalyses) {
return false;
}
$analysisids = array();
foreach ($responseanalyses as $responseanalysis) {
$analysisforsubpart = $this->analysis->get_analysis_for_subpart($responseanalysis->variant, $responseanalysis->subqid);
$class = $analysisforsubpart->get_response_class($responseanalysis->aid);
$class->add_response($responseanalysis->response, $responseanalysis->credit);
$analysisids[] = $responseanalysis->id;
}
list($sql, $params) = $DB->get_in_or_equal($analysisids);
$counts = $DB->get_records_select('question_response_count', "analysisid {$sql}", $params);
foreach ($counts as $count) {
$responseanalysis = $responseanalyses[$count->analysisid];
$analysisforsubpart = $this->analysis->get_analysis_for_subpart($responseanalysis->variant, $responseanalysis->subqid);
$class = $analysisforsubpart->get_response_class($responseanalysis->aid);
$class->set_response_count($responseanalysis->response, $count->try, $count->rcount);
}
return $this->analysis;
}
/**
* Find time of non-expired analysis in the database.
*
* @param \qubaid_condition $qubaids check for the analysis of which question usages?
* @param string $whichtries check for the analysis of which tries?
* @return integer|boolean Time of cached record that matches this qubaid_condition or false if none found.
*/
public function get_last_analysed_time($qubaids, $whichtries) {
global $DB;
$timemodified = time() - self::TIME_TO_CACHE;
return $DB->get_field_select('question_response_analysis', 'timemodified',
'hashcode = ? AND whichtries = ? AND questionid = ? AND timemodified > ?',
array($qubaids->get_hash_code(), $whichtries, $this->questiondata->id, $timemodified),
IGNORE_MULTIPLE);
}
}