C Style Date string - Return date from Julian date

[ssimop]

C Style Date string - Julian date

I understand that s.time("%y") gives today's day of year as decimal number, ie. julian day in this year.
I also understand that this function is now obsolete and it is replaced by str.timeformat. I wonder whether anyone has implemented the oposite function - action, ie to return the date-month string from the julian day in this year. Any advice much appreciated.