Python3 convert Julian date to standard date
Question: I have a string as Julian date like `"16152"` meaning 152'nd day of 2016 or
`"15234"` meaning 234'th day of 2015.

How can I convert these Julian dates to format like `20/05/2016` using Python
3 standard library?

I can get the year 2016 like this: `date = 20 + julian[0:1]`, where `julian`
is the string containing the Julian date, but how can I calculate the rest
according to 1th of January?


Answer: The
[`.strptime()`](https://docs.python.org/3.5/library/datetime.html#datetime.datetime.strptime)
method supports the _day of year_ format:

    
    
    >>> import datetime
    >>>
    >>> datetime.datetime.strptime('16234', '%y%j').date()
    datetime.date(2016, 8, 21)
    

And then you can use
[`strftime()`](https://docs.python.org/3.5/library/datetime.html#datetime.date.strftime)
to reformat the date

    
    
    >>> date = datetime.date(2016, 8, 21)
    >>> date.strftime('%d/%m/%Y')
    '21/08/2016'
    

