How convert decimal to POSIX time

Question

I use a function from here to calculate the sunrise and sunset and it returns:

         sunrise           sunset
6.49055593325792 18.2873900837081
         


        

Answer 1

First convert the decimal representation to hours and minutes (if I understand it right)

x <- c(6.49055593325792, 18.2873900837081)
# if 6.49 equals 6.49 hours, then do this.
x.m <- paste(floor(x), round((x-floor(x))*60), sep=":")

> x.m
# [1] "6:29"  "18:17"

> strptime(x.m, format="%H:%M")    
# [1] "2013-01-23 06:29:00" "2013-01-23 18:17:00"