Few days ago I was working on some python scripts that needed to iterate back and forth through calendar dates. Working with dates in python is pretty easy, due to its datetime package.
Basically is like this:
#!/usr/bin/env python import datetime start_date = datetime.date( year = 2010, month = 2, day = 1 ) end_date = datetime.date( year = 2010, month = 1, day = 1 ) list = [] if start_date <= end_date: for n in range( ( end_date - start_date ).days + 1 ): list.append( start_date + datetime.timedelta( n ) ) else: for n in range( ( start_date - end_date ).days + 1 ): list.append( start_date - datetime.timedelta( n ) ) for d in list: print d
This works, but is somewhat lame and not quite reusable. The most “python-ish” way to do it is to create a generator function that will yield the current date and can be used in a for loop. So I did it:
#!/usr/bin/env python import datetime def daterange( start_date, end_date ): if start_date <= end_date: for n in range( ( end_date - start_date ).days + 1 ): yield start_date + datetime.timedelta( n ) else: for n in range( ( start_date - end_date ).days + 1 ): yield start_date - datetime.timedelta( n ) start = datetime.date( year = 2010, month = 2, day = 1 ) end = datetime.date( year = 2010, month = 1, day = 1 ) for date in daterange( start, end ): print date
Much more elegant 
Nice. Thanks for sharing.