I sometimes need to determine the day of the year corresponding to today's date. The day of year starts with January 1 as day 1 and for 2017, December 31 is day 365. You can find sites online that will provide those values, e.g. Day Numbers for 2017 or NOAA's DOY Calendar. Or, on a system with Python installed, e.g., Linux or OS X, you can use the datetime module to obtain the day of the year corresponding to the current date as shown below:
$ python Python 2.7.10 (default, Oct 23 2015, 19:19:21) [GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import datetime >>> datetime.datetime.today().timetuple().tm_yday 280 >>> exit() $
Since today is October 7 of the year 2017, the day of the year is 280.
If you want to obtain the day of year (DOY) for another date, you can use
datetime.date(year, month, day).timetuple().tm_yday
where year is the relevant year, month is the month,
and day is the day of interest. E.g., March 1, 2017 is DOY 60:
>>> import datetime >>> datetime.date(2017, 3, 1).timetuple().tm_yday 60 >>>