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Calculate the total time based on the summary and time of iCalendar Events
from icalendar import Calendar
from datetime import timedelta
from itertools import groupby
from operator import itemgetter
def calculate_time(event):
start = event['DTSTART'].dt
end = event['DTEND'].dt
return end - start
def lecturize(event):
summary = str(event['SUMMARY'])
for lecture in lectures:
if lecture in summary:
return lecture
def time_per_lecture(events):
sorted_events = sorted(events, key=itemgetter(0))
for key, group in groupby(sorted_events, itemgetter(0)):
yield (key, sum(map(itemgetter(1), group), timedelta()))
lectures = ['An1I', 'Math1I', 'Bsys1', 'CN1', 'EnglHTw', 'Prog1', 'ICTh']
file = open('examtime_export.ics', 'rb')
cal = Calendar.from_ical(
events = [(lecturize(e), calculate_time(e)) for e in cal.walk('vevent')]
used_time = dict(time_per_lecture(events))
total_time = sum(used_time.values(), timedelta())
for lecture, time in used_time.items():
print('{}\t{}h'.format(lecture, time.total_seconds() / 3600))
print('TOTAL\t{}h'.format(total_time.total_seconds() / 3600))

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lucbouge commented Jul 14, 2016

Dear Lukas,

Thanks for your Python script. Congrats for the nice style. I used it for checking next year schedules at my school, ENS Rennes in Brittany, France.

I encountered a problem. If the schedule does not contains the lectures only, then lecturize my return None, so that the sorting phase of time_per_lecture fails.

You might wish to add a filter to remove all None tuples from the events list. Here is my solution, although using filter would probably be more elegant.

events = [(lecturize(e), calculate_time(e)) for e in cal.walk('vevent')]
events = [e for e in events if e[0] != None]

Another possibility is to filter out at the construction of the events list.

Best regards,


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