decimal year to datetime

decimal_to_year.py

from datetime import datetime ,timedelta
import sys

given_year = float(sys.argv[1])
base = datetime(int(given_year),1,1)
year_rem = given_year - int(given_year)

calc_date = (base + timedelta(seconds = (base.replace(year = base.year+1) - base).total_seconds() * year_rem ))
print(calc_date.strftime("%d %b %Y"))

python decimal_to_year.py 2019.978082191781
08 Jan 2020