Find the first day of specific years ago from current day using lubridate package

I’m able to find the date certain years ago from today with code below:

library(lubridate)
today <- format(Sys.Date())
pre_3years <- ymd(today) - years(3)
pre_3years 

Out:

[1] "2018-12-27"

In fact, I hope to get the first day of pre_3year, which is 2018-01-01 for this example, how could I get that using lubridate package in R? Thanks.

>Solution :

You may use floor_date from lubridate to get 1st day of the year.

library(lubridate)
first_day_of_n_prev <- function(x) {
  floor_date(Sys.Date() - years(x), 'year')  
}

first_day_of_n_prev(3)
#[1] "2018-01-01"

first_day_of_n_prev(2)
#[1] "2019-01-01"