python中有效的日期范围重叠计算？ [英] Efficient date range overlap calculation in python?

问题描述

我有两个日期范围，每个范围由开始和结束日期确定（显然，datetime.date（）实例）。两个范围可以重叠。我需要重叠的天数。当然，我可以预先填写两个范围内的所有日期的两个集合，并且执行一个设置的交集，但是这可能是低效的？除了另一个解决方案之外，还有一个更好的方法，使用一个长的if-elif部分涵盖所有情况？ / p>

解决方案

• 确定最后两个开始日期和最后两个结束日期。 li>
  
• 通过减去timedelta计算时间。


• 如果增量是正数，那就是重叠的天数。

以下是一个示例计算：

 >> ; from datetime import datetime 
>>>>从集合导入namedtuple 
>>> Range = namedtuple（'Range'，['start'，'end']）
>>> r1 =范围（start = datetime（2012，1，15），end = datetime（2012，5，10））
>>> r2 = Range（start = datetime（2012，3，20），end = datetime（2012，9，15））
>>> latest_start = max（r1.start，r2.start）
>>> earliest_end = min（r1.end，r2.end）
>>> overlap =（earliest_end  -  latest_start）.days + 1 
>>>重叠
 52 
  

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 days of the overlap. Of course I can pre-fill two sets with all dates within both ranges and the perform a set intersection but this is possibly inefficient...is there a better way apart from another solution using a long if-elif section covering all cases ?

解决方案

• Determine the latest of the two start dates and the earliest of the two end dates.
• Compute the timedelta by subtracting them.
• If the delta is positive, that is the number of days of overlap.

Here is an example calculation:

>>> from datetime import datetime
>>> from collections import namedtuple
>>> Range = namedtuple('Range', ['start', 'end'])
>>> r1 = Range(start=datetime(2012, 1, 15), end=datetime(2012, 5, 10))
>>> r2 = Range(start=datetime(2012, 3, 20), end=datetime(2012, 9, 15))
>>> latest_start = max(r1.start, r2.start)
>>> earliest_end = min(r1.end, r2.end)
>>> overlap = (earliest_end - latest_start).days + 1
>>> overlap
52

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