Create end of the month date from a date variable

Question

I have a large data frame with date variables, which reflect first day of the month. Is there an easy way to create a new data frame date variable that represents the last d

Answer 1

To get the end of months you could just create a Date vector containing the 1st of all the subsequent months and subtract 1 day.

date.end.month <- seq(as.Date("2012-02-01"),length=4,by="months")-1
date.end.month
[1] "2012-01-31" "2012-02-29" "2012-03-31" "2012-04-30"

Answer 2

library(lubridate)
 as.Date("2019-09-01") - days(1)
[1] "2019-08-31"

or

library(lubridate)
 as.Date("2019-09-01") + months(1) - days(1)
[1] "2019-09-30"