Got it, I needed to use the when/otherwise construct - code below def getSunday(day):
day = day.cast("date") sun = next_day(day, "Sunday") n = datediff(sun,day) x = when(n==7,day).otherwise(sun) return x On 10 January 2016 at 08:41, Franc Carter <franc.car...@gmail.com> wrote: > > My Python is not particularly good, so I'm afraid I don't understand what > that mean > > cheers > > > On 9 January 2016 at 14:45, Franc Carter <franc.car...@gmail.com> wrote: > >> >> Hi, >> >> I'm trying to write a short function that returns the last sunday of the >> week of a given date, code below >> >> def getSunday(day): >> >> day = day.cast("date") >> >> sun = next_day(day, "Sunday") >> >> n = datediff(sun,day) >> >> if (n == 7): >> >> return day >> >> else: >> >> return sun >> >> >> this gives me >> >> ValueError: Cannot convert column into bool: >> >> >> Can someone point out what I am doing wrong >> >> thanks >> >> >> -- >> Franc >> > > > > -- > Franc > -- Franc