How do I convert date to number of days in R

Question

How do I convert date to number of days, starting from the first day of the year.

How do I convert the following to the expected result below?

   Dat         


        

Answer 1

Here's a solution using the lubridate package:

library(lubridate)

x <- c("02/01/2000", "20/02/2000", "12/12/2000", "13/01/2001")
date <- dmy(x)

days <- yday(date) - 1 # so Jan 1 = day 0 
total_days <- cumsum(days)