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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/>.
namespace quiz_statistics;
defined('MOODLE_INTERNAL') || die();
/**
* The statistics calculator returns an instance of this class which contains the calculated statistics.
*
* These quiz statistics calculations are described here :
*
* http://docs.moodle.org/dev/Quiz_statistics_calculations#Test_statistics
*
* @package quiz_statistics
* @copyright 2013 The Open University
* @author James Pratt me@jamiep.org
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class calculated {
/**
* @param string $whichattempts which attempts to use, represented internally as one of the constants as used in
* $quiz->grademethod ie.
* QUIZ_GRADEAVERAGE, QUIZ_GRADEHIGHEST, QUIZ_ATTEMPTLAST or QUIZ_ATTEMPTFIRST
* we calculate stats based on which attempts would affect the grade for each student,
* the default null value is used when constructing an instance whose values will be
* populated from a db record.
*/
public function __construct($whichattempts = null) {
if ($whichattempts !== null) {
$this->whichattempts = $whichattempts;
}
}
/**
* @var int which attempts we are calculating calculate stats from.
*/
public $whichattempts;
/* Following stats all described here : http://docs.moodle.org/dev/Quiz_statistics_calculations#Test_statistics */
public $firstattemptscount = 0;
public $allattemptscount = 0;
public $lastattemptscount = 0;
public $highestattemptscount = 0;
public $firstattemptsavg;
public $allattemptsavg;
public $lastattemptsavg;
public $highestattemptsavg;
public $median;
public $standarddeviation;
public $skewness;
public $kurtosis;
public $cic;
public $errorratio;
public $standarderror;
/**
* @var int time these stats where calculated and cached.
*/
public $timemodified;
/**
* Count of attempts selected by $this->whichattempts
*
* @return int
*/
public function s() {
return $this->get_field('count');
}
/**
* Average grade for the attempts selected by $this->whichattempts
*
* @return float
*/
public function avg() {
return $this->get_field('avg');
}
/**
* Get the right field name to fetch a stat for these attempts that is calculated for more than one $whichattempts (count or
* avg).
*
* @param string $field name of field
* @return int|float
*/
protected function get_field($field) {
$fieldname = calculator::using_attempts_string_id($this->whichattempts).$field;
return $this->{$fieldname};
}
/**
* @param $course
* @param $cm
* @param $quiz
* @return array to display in table or spreadsheet.
*/
public function get_formatted_quiz_info_data($course, $cm, $quiz) {
// You can edit this array to control which statistics are displayed.
$todisplay = array('firstattemptscount' => 'number',
'allattemptscount' => 'number',
'firstattemptsavg' => 'summarks_as_percentage',
'allattemptsavg' => 'summarks_as_percentage',
'lastattemptsavg' => 'summarks_as_percentage',
'highestattemptsavg' => 'summarks_as_percentage',
'median' => 'summarks_as_percentage',
'standarddeviation' => 'summarks_as_percentage',
'skewness' => 'number_format',
'kurtosis' => 'number_format',
'cic' => 'number_format_percent',
'errorratio' => 'number_format_percent',
'standarderror' => 'summarks_as_percentage');
// General information about the quiz.
$quizinfo = array();
$quizinfo[get_string('quizname', 'quiz_statistics')] = format_string($quiz->name);
$quizinfo[get_string('coursename', 'quiz_statistics')] = format_string($course->fullname);
if ($cm->idnumber) {
$quizinfo[get_string('idnumbermod')] = $cm->idnumber;
}
if ($quiz->timeopen) {
$quizinfo[get_string('quizopen', 'quiz')] = userdate($quiz->timeopen);
}
if ($quiz->timeclose) {
$quizinfo[get_string('quizclose', 'quiz')] = userdate($quiz->timeclose);
}
if ($quiz->timeopen && $quiz->timeclose) {
$quizinfo[get_string('duration', 'quiz_statistics')] =
format_time($quiz->timeclose - $quiz->timeopen);
}
// The statistics.
foreach ($todisplay as $property => $format) {
if (!isset($this->$property) || !$format) {
continue;
}
$value = $this->$property;
switch ($format) {
case 'summarks_as_percentage':
$formattedvalue = quiz_report_scale_summarks_as_percentage($value, $quiz);
break;
case 'number_format_percent':
$formattedvalue = quiz_format_grade($quiz, $value) . '%';
break;
case 'number_format':
// 2 extra decimal places, since not a percentage,
// and we want the same number of sig figs.
$formattedvalue = format_float($value, $quiz->decimalpoints + 2);
break;
case 'number':
$formattedvalue = $value + 0;
break;
default:
$formattedvalue = $value;
}
$quizinfo[get_string($property, 'quiz_statistics',
calculator::using_attempts_lang_string($this->whichattempts))] = $formattedvalue;
}
return $quizinfo;
}
/**
* @var array of names of properties of this class that are cached in db record.
*/
protected $fieldsindb = array('whichattempts', 'firstattemptscount', 'allattemptscount', 'firstattemptsavg', 'allattemptsavg',
'lastattemptscount', 'highestattemptscount', 'lastattemptsavg', 'highestattemptsavg',
'median', 'standarddeviation', 'skewness',
'kurtosis', 'cic', 'errorratio', 'standarderror');
/**
* Cache the stats contained in this class.
*
* @param $qubaids \qubaid_condition
*/
public function cache($qubaids) {
global $DB;
$toinsert = new \stdClass();
foreach ($this->fieldsindb as $field) {
$toinsert->{$field} = $this->{$field};
}
$toinsert->hashcode = $qubaids->get_hash_code();
$toinsert->timemodified = time();
// Fix up some dodgy data.
if (isset($toinsert->errorratio) && is_nan($toinsert->errorratio)) {
$toinsert->errorratio = null;
}
if (isset($toinsert->standarderror) && is_nan($toinsert->standarderror)) {
$toinsert->standarderror = null;
}
// Store the data.
$DB->insert_record('quiz_statistics', $toinsert);
}
/**
* Given a record from 'quiz_statistics' table load the data into the properties of this class.
*
* @param $record \stdClass from db.
*/
public function populate_from_record($record) {
foreach ($this->fieldsindb as $field) {
$this->$field = $record->$field;
}
$this->timemodified = $record->timemodified;
}
}