Efficient date range overlap calculation in python?

Question

I have two date ranges where each range is determined by a start and end date (obviously, datetime.date() instances). The two ranges can overlap or not. I need the number of

Answer 1

I implemented a TimeRange class as you can see below.

The get_overlapped_range first negates all the non overlapped options by a simple condition, and then calculate the overlapped range by considering all the possible options.

To get the amount of days you'll need to take the TimeRange value that was returned from get_overlapped_range and divide the duration by 60*60*24.

class TimeRange(object):
    def __init__(self, start, end):
        self.start = start
        self.end = end
        self.duration = self.end - self.start

    def is_overlapped(self, time_range):
        if max(self.start, time_range.start) < min(self.end, time_range.end):
            return True
        else:
            return False

    def get_overlapped_range(self, time_range):
        if not self.is_overlapped(time_range):
            return

        if time_range.start >= self.start:
            if self.end >= time_range.end:
                return TimeRange(time_range.start, time_range.end)
            else:
                return TimeRange(time_range.start, self.end)
        elif time_range.start < self.start:
            if time_range.end >= self.end:
                return TimeRange(self.start, self.end)
            else:
                return TimeRange(self.start, time_range.end)

    def __repr__(self):
        return '{0} ------> {1}'.format(*[time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(d))
                                          for d in [self.start, self.end]])