Another lubridate function that has saved me from writing some really janky code is rollback() which allows you to roll a date back to the last day of the previous month or first day of the month!

lubridate::rollback.md

Code:

library(lubridate)
my_date <- ymd("2018-11-23")
rollback(my_date)

Output:

[1] "2018-10-31"

Code:

rollback(my_date, roll_to_first = TRUE)

Output:

[1] "2018-11-01"