Splitting a time range into hours? - php

Question

I'm currently working with a data set containing a start time, date, and a duration in seconds, and need to be able to split the range of times from start time to (start time + duration, e.g. end time) into hour "buckets" if you will.
So for instance, a start time of 08:30:00 with duration 9000 seconds (2.5 hours) covers hour 08 from 8:30:00 to 09:00:00 for 1800 seconds, hour 09 until 10:00:00 for 3600 seconds, etc. up to the end time of 11:00:00.
What would be the best way possible to do this? I'm working in PHP however a general algorithmic solution would still be incredibly helpful.
My current approach is as follows:
1. Calculate the hour difference between both times (round up to next hour if there's a non-zero number of minutes)
2. Let session progress = 0
3. Iterate the range from 1 to hour difference:
1. Let the current bucket duration = min(3600, duration)
2. Let the duration = max(0, duration - current bucket duration)
3. Let bucket start time = start time + session progress
4. Let bucket end time = bucket start time + current bucket duration
5. Do work based on these values
6. Let session progress += current bucket duration
My PHP implementation of this is as follows:
foreach ($csv as $listen_record) {
$start_dt = $listen_record['Date'] . ' ' . $listen_record['Time'];
$session_duration = $listen_record['Duration'];
$session_start_time = date_create_from_format($datetime_format, $start_dt);
$session_end_time = clone $session_start_time;
date_add($session_end_time, date_interval_create_from_date_string($session_duration . ' seconds'));
$diff = date_diff($session_end_time, $session_start_time);
$hourdiff = $diff->h;
if ($diff->m > 0)
$hourdiff += 1;
$session_progress = 0;
foreach (range(1, $hourdiff) as $hour) {
$record_duration = min(3600, $session_duration);
$session_duration = max(0, $session_duration - $record_duration);
$record_start_time = clone $session_start_time;
date_add($record_start_time, date_interval_create_from_date_string($session_progress . ' seconds'));
$record_end_time = clone $record_start_time;
date_add($record_end_time, date_interval_create_from_date_string($record_duration . ' seconds'));
if ($record_start_time == $record_end_time)
continue;
// DO WORK...
$session_progress += $record_duration;
}
}
This kind of works to separate each record into hour long buckets however gives some weird results for some cases (particularly cases where the range crosses into a new day) and doesn't align to actual wall clock hours.
Is there a better way to do this that can actually align to wall clock hours and not freak out when it has to cope with durations that cross over midnight?
Thanks!

Answer 1

Update: I managed to solve this on my own so I'm posting how I did it just in case anyone else needs to do similar.
Basically I did it by creating a range between the start and end timestamp, and filtering out every time stamp apart from start and end that isnt a multiple of 3600 or just before 3600. This gives me the wall clock hours in the middle of the range as timestamps. I can then split the array into chunks of 2 which contains the slot start time and end time.
My PHP code is as follows and now actually works:
function is_wall_clock_aligned_hour_boundary($timestamp) {
return ($timestamp % (60*60) === 0) || (($timestamp + 1) % (60*60) === 0);
}
function create_slot_object($slot) {
$start_time = reset($slot);
$end_time = end($slot);
$duration = $end_time - $start_time;
return array(
'startTime' => convert_timestamp_to_datetime($start_time),
'endTime' => convert_timestamp_to_datetime($end_time),
'duration' => $duration
);
}
function make_slots(DateTime $start_time, $duration) {
$start_timestamp = $start_time->getTimestamp();
$end_time = clone $start_time;
date_add($end_time, date_interval_create_from_date_string("$duration seconds"));
$end_timestamp = $end_time->getTimestamp();
$time_sequence = range($start_timestamp, $end_timestamp);
$slot_boundaries = array_filter($time_sequence, 'is_wall_clock_aligned_hour_boundary');
array_unshift($slot_boundaries, $start_timestamp);
array_push($slot_boundaries, $end_timestamp);
$slots = array_chunk($slot_boundaries, 2);
return array_map('create_slot_object', $slots);
}