Your IP : 192.168.165.1
<?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 periodic extends base {
/**
* The periodicity of the predictions / training data generation.
*
* @return \DateInterval
*/
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.
*
* @param \core_analytics\analysable $analysable
* @return bool
*/
public function is_valid_analysable(\core_analytics\analysable $analysable) {
if (!$analysable->get_start()) {
return false;
}
return true;
}
/**
* define_ranges
*
* @return array
*/
protected function define_ranges() {
$periodicity = $this->periodicity();
if ($this->analysable->get_end()) {
$end = (new \DateTimeImmutable())->setTimestamp($this->analysable->get_end());
}
$nexttime = (new \DateTimeImmutable())->setTimestamp($this->get_first_start());
$now = new \DateTimeImmutable('now', \core_date::get_server_timezone_object());
$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.');
}
}
$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;
}
/**
* Overwritten as all generated rows are comparable.
*
* @return bool
*/
public function include_range_info_in_training_data() {
return false;
}
/**
* Overwritting as the last range may be for prediction.
*
* @return array
*/
public function get_training_ranges() {
// Cloning the array.
$trainingranges = $this->ranges;
foreach ($trainingranges as $rangeindex => $range) {
if (!$this->ready_to_train($range)) {
unset($trainingranges[$rangeindex]);
}
}
return $trainingranges;
}
/**
* Allows child classes to update the last range provided.
*
* @param array $ranges
* @return array
*/
protected function update_last_range(array $ranges) {
return $ranges;
}
}