Extract day of year and Julian day from a string date

Question

I have a string \"2012.11.07\" in python. I need to convert it to date object and then get an integer value of day of year and also Julian day

Answer 1

According to this article there is an unpublished one-line formula created by Fliegel and Van Flandern to calculate an Gregorian Date to an Julian Date:

JD = 367 * year - 7 * (year + (month + 9)/12)/4 - 3 * ((year + (month - 9)/7)/100 + 1)/4 + 275 * month/9 + day + 1721029

This was compacted by P. M. Muller and R. N. Wimberly of the Jet Propulsion Laboratory, Pasadena, California for dates after March of 1900 to:

JD = 367 * year - 7 * (year + (month + 9)/12)/4 + 275 * month/9 + day + 1721014

These formulas are off by 0.5, so just subtract 0.5 from the formulas.

Use some string manupulation to actually extract the data and you will be good

>>> year, month, day = map(int,"2018.11.02".split("."))
>>> 367 * year - 7 * (year + (month + 9)/12)/4 + 275 * month/9 + day + 1721014 - 0.5
2458424.5