How to convert Python datetime dates to decimal/float years

Question

I am looking for a way to convert datetime objects to decimal(/float) year, including fractional part. Example:

>>> obj = SomeObjet()
>>> o         


        

Answer 1

This is a little simpler way than the other solutions:

import datetime
def year_fraction(date):
    start = datetime.date(date.year, 1, 1).toordinal()
    year_length = datetime.date(date.year+1, 1, 1).toordinal() - start
    return date.year + float(date.toordinal() - start) / year_length

>>> print year_fraction(datetime.datetime.today())
2016.32513661

Note that this calculates the fraction based on the start of the day, so December 31 will be 0.997, not 1.0.