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MDL-65588 analytics: New models for student accesses

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David Monllaó 2019-05-17 12:24:13 +02:00
parent 7d8ed90757
commit 2d9280e0df
21 changed files with 1079 additions and 89 deletions
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111
analytics/classes/local/time_splitting/after_start.php Normal file
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@ -0,0 +1,111 @@
<?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/>.
/**
* Time splitting method that generates predictions X days/weeks/months after the analysable start.
*
* @package core_analytics
* @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_analytics\local\time_splitting;
defined('MOODLE_INTERNAL') || die();
/**
* Time splitting method that generates predictions X days/weeks/months after the analysable start.
*
* @package core_analytics
* @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class after_start extends \core_analytics\local\time_splitting\base implements before_now {
/**
* The period we should wait until we generate predictions for this.
*
* @param \core_analytics\analysable $analysable
* @return \DateInterval
*/
abstract protected function wait_period(\core_analytics\analysable $analysable);
/**
* Returns whether the course can be processed by this time splitting method or not.
*
* @param \core_analytics\analysable $analysable
* @return bool
*/
public function is_valid_analysable(\core_analytics\analysable $analysable) {
if (!$analysable->get_start()) {
return false;
}
$predictionstart = $this->get_prediction_interval_start($analysable);
if ($analysable->get_start() > $predictionstart) {
// We still need to wait.
return false;
}
return true;
}
/**
* This time-splitting method returns one single range, the start to two days before the end.
*
* @return array The list of ranges, each of them including 'start', 'end' and 'time'
*/
protected function define_ranges() {
$now = time();
$ranges = [
[
'start' => $this->analysable->get_start(),
'end' => $now,
'time' => $now,
]
];
return $ranges;
}
/**
* Whether to cache or not the indicator calculations.
*
* @return bool
*/
public function cache_indicator_calculations(): bool {
return false;
}
/**
* Calculates the interval start time backwards, from now.
*
* @param \core_analytics\analysable $analysable
* @return int
*/
protected function get_prediction_interval_start(\core_analytics\analysable $analysable) {
// The prediction time is always time(). We don't want to reuse the firstanalysis time
// because otherwise samples (e.g. students) which start after the analysable (e.g. course)
// start would use an incorrect analysis interval.
$predictionstart = new \DateTime('now');
$predictionstart->sub($this->wait_period($analysable));
return $predictionstart->getTimestamp();
}
}

97
analytics/classes/local/time_splitting/past_periodic.php Normal file
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@ -0,0 +1,97 @@
<?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/>.
/**
* Time splitting method that generates predictions regularly.
*
* @package core_analytics
* @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_analytics\local\time_splitting;
defined('MOODLE_INTERNAL') || die();
/**
* Time splitting method that generates predictions periodically.
*
* @package core_analytics
* @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class past_periodic extends periodic implements before_now {
/**
* Gets the next range with start on the provided time.
*
* The next range is based on the past period so we substract this
* range's periodicity from $time.
*
* @param \DateTimeImmutable $time
* @return array
*/
protected function get_next_range(\DateTimeImmutable $time) {
$end = $time->getTimestamp();
$start = $time->sub($this->periodicity())->getTimestamp();
if ($start < $this->analysable->get_start()) {
// We skip the first range generated as its start is prior to the analysable start.
return false;
}
return [
'start' => $start,
'end' => $end,
'time' => $end
];
}
/**
* Get the start of the first time range.
*
* @return int A timestamp.
*/
protected function get_first_start() {
return $this->analysable->get_start();
}
/**
* Guarantees that the last range dates end right now.
*
* @param array $ranges
* @return array
*/
protected function update_last_range(array $ranges) {
$lastrange = end($ranges);
if ($lastrange['time'] > time()) {
// We just need to wait in this case.
return $lastrange;
}
$timetoenddiff = time() - $lastrange['time'];
$ranges[count($ranges) - 1] = [
'start' => $lastrange['start'] + $timetoenddiff,
'end' => $lastrange['end'] + $timetoenddiff,
'time' => $lastrange['time'] + $timetoenddiff,
];
return $ranges;
}
}

88
analytics/classes/local/time_splitting/periodic.php
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@ -42,6 +42,21 @@ abstract class periodic extends base {
*/
abstract protected function periodicity();
/**
* Gets the next range with start on the provided time.
*
* @param \DateTimeImmutable $time
* @return array
*/
abstract protected function get_next_range(\DateTimeImmutable $time);
/**
* Get the start of the first time range.
*
* @return int A timestamp.
*/
abstract protected function get_first_start();
/**
* Returns whether the analysable can be processed by this time splitting method or not.
*
@ -67,25 +82,42 @@ abstract class periodic extends base {
if ($this->analysable->get_end()) {
$end = (new \DateTimeImmutable())->setTimestamp($this->analysable->get_end());
}
$next = (new \DateTimeImmutable())->setTimestamp($this->get_first_start());
$nexttime = (new \DateTimeImmutable())->setTimestamp($this->get_first_start());
$now = new \DateTimeImmutable('now', \core_date::get_server_timezone_object());
$ranges = [];
while ($next < $now &&
(empty($end) || $next < $end)) {
$range = $this->get_next_range($next);
if ($range) {
$ranges[] = $range;
$range = $this->get_next_range($nexttime);
if (!$range) {
$nexttime = $nexttime->add($periodicity);
$range = $this->get_next_range($nexttime);
if (!$range) {
throw new \coding_exception('The get_next_range implementation is broken. The difference between two consecutive
ranges can not be more than the periodicity.');
}
$next = $next->add($periodicity);
}
$nextrange = $this->get_next_range($next);
if ($this->ready_to_predict($nextrange) && (empty($end) || $next < $end)) {
// Add the next one if we have not reached the analysable end yet.
// It will be used to get predictions.
$ranges[] = $nextrange;
$ranges = [];
$endreached = false;
while (($this->ready_to_predict($range) || $this->ready_to_train($range)) && !$endreached) {
$ranges[] = $range;
$nexttime = $nexttime->add($periodicity);
$range = $this->get_next_range($nexttime);
$endreached = (!empty($end) && $nexttime > $end);
}
if ($ranges && !$endreached) {
// If this analysable is not finished we adjust the start and end of the last element in $ranges
// so that it ends in time().The reason is that the start of these ranges is based on the analysable
// start and the end is calculated based on the start. This is to prevent the same issue we had in MDL-65348.
//
// An example of the situation we want to avoid is:
// A course started on a Monday, in 2015. It has no end date. Now the system is upgraded to Moodle 3.8, which
// includes this code. This happens on Wednesday. Periodic ranges (e.g. weekly) will be calculated from a Monday
// so the data provided by the time-splitting method would be from Monday to Monday, when we really want to
// provide data from Wednesday to the past Wednesday.
$ranges = $this->update_last_range($ranges);
}
return $ranges;
@ -119,34 +151,12 @@ abstract class periodic extends base {
}
/**
* The next range is based on the past period.
* Allows child classes to update the last range provided.
*
* @param \DateTimeImmutable $next
* @param array $ranges
* @return array
*/
protected function get_next_range(\DateTimeImmutable $next) {
$end = $next->getTimestamp();
$start = $next->sub($this->periodicity())->getTimestamp();
if ($start < $this->analysable->get_start()) {
// We skip the first range generated as its start is prior to the analysable start.
return false;
}
return [
'start' => $start,
'end' => $end,
'time' => $end
];
}
/**
* Get the start of the first time range.
*
* @return int A timestamp.
*/
protected function get_first_start() {
return $this->analysable->get_start();
protected function update_last_range(array $ranges) {
return $ranges;
}
}

17
analytics/classes/local/time_splitting/upcoming_periodic.php
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@ -36,15 +36,18 @@ defined('MOODLE_INTERNAL') || die();
abstract class upcoming_periodic extends periodic implements after_now {
/**
* The next range indicator calculations should be based on upcoming dates.
* Gets the next range with start on the provided time.
*
* @param \DateTimeImmutable $next
* The next range is based on the upcoming period so we add this
* range's periodicity to $time.
*
* @param \DateTimeImmutable $time
* @return array
*/
protected function get_next_range(\DateTimeImmutable $next) {
protected function get_next_range(\DateTimeImmutable $time) {
$start = $next->getTimestamp();
$end = $next->add($this->periodicity())->getTimestamp();
$start = $time->getTimestamp();
$end = $time->add($this->periodicity())->getTimestamp();
return [
'start' => $start,
'end' => $end,
@ -87,7 +90,7 @@ abstract class upcoming_periodic extends periodic implements after_now {
return $firstanalysis;
}
// This analysable has not yet been analysed, the start is therefore now (-1 so ready_to_predict can be executed).
return time() - 1;
// This analysable has not yet been analysed, the start is therefore now.
return time();
}
}