/**
* Get the quiz and question statistics, either by loading the cached results,
* or by recomputing them.
*
* @param object $quiz the quiz settings.
* @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.
* @param array $groupstudents students in this group.
* @param array $questions full question data.
* @return array with 4 elements:
* - $quizstats The statistics for overall attempt scores.
* - $questionstats array of \core_question\statistics\questions\calculated objects keyed by slot.
* - $subquestionstats array of \core_question\statistics\questions\calculated_for_subquestion objects keyed by question id.
*/
public function get_quiz_and_questions_stats($quiz, $whichattempts, $groupstudents, $questions)
{
$qubaids = quiz_statistics_qubaids_condition($quiz->id, $groupstudents, $whichattempts);
$qcalc = new \core_question\statistics\questions\calculator($questions);
$quizcalc = new quiz_statistics_calculator();
if ($quizcalc->get_last_calculated_time($qubaids) === false) {
// Recalculate now.
list($questionstats, $subquestionstats) = $qcalc->calculate($qubaids);
$quizstats = $quizcalc->calculate($quiz->id, $whichattempts, $groupstudents, count($questions), $qcalc->get_sum_of_mark_variance());
if ($quizstats->s()) {
$this->analyse_responses_for_all_questions_and_subquestions($qubaids, $questions, $subquestionstats);
}
} else {
$quizstats = $quizcalc->get_cached($qubaids);
list($questionstats, $subquestionstats) = $qcalc->get_cached($qubaids);
}
return array($quizstats, $questionstats, $subquestionstats);
}
