Proyectos de Subversion Moodle

<?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

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//

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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

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// 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 object full question data from db. */

    protected $questiondata;

    /**

     * @var analysis_for_question|analysis_for_question_all_tries

     */

    public $analysis;

    /**

     * @var int used during calculations, so all results are stored with the same timestamp.

     */

    protected $calculationtime;

    /**

     * @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 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) {

        $this->calculationtime = time();

        // 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, $this->calculationtime);

        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;

        $timemodified = self::get_last_analysed_time($qubaids, $whichtries);

        // Variable name 'analyses' is the plural of 'analysis'.

        $responseanalyses = $DB->get_records('question_response_analysis',

                ['hashcode' => $qubaids->get_hash_code(), 'whichtries' => $whichtries,

                        'questionid' => $this->questiondata->id, 'timemodified' => $timemodified]);

        if (!$responseanalyses) {

            return false;

        }

        $analysisids = [];

        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;

        }

        [$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;

        return $DB->get_field('question_response_analysis', 'MAX(timemodified)',

                ['hashcode' => $qubaids->get_hash_code(), 'whichtries' => $whichtries,

                        'questionid' => $this->questiondata->id]);

    }

}