Assigning value to a column based on periods derived from other columns using vector approach in R

Question

I have a df like this:

x <- data.frame("date1" = c("2018-09-12","2018-09-18", "2019-06-23"), "date2" = c("2018-09-10","2018-09-13","2018-12-12"))
> x
       date1      date2
1 2018-09-12 2018-09-10
2 2018-09-18 2018-09-13
3 2019-06-23 2018-12-12

Now I would do an unique on date1 which will result in unique date value. I would then create a new column and assign value of period to it based on date in col date2, like this

     date1      date2     period
1 2018-09-12 2018-09-10   0
2 2018-09-18 2018-09-13   1 (as period 1: is 2018-09-12 to 2018-09-18 and date2 lies in it)
3 2019-06-23 2018-12-12   2  (as period 2: is 2018-09-18 to 2019-06-23 and date2 lies in that)

Is there is a way to do it in a vector form in R. Thanks

Answer 1

Can you try this?

periods = as.Date(sort(unique(x$date1)))
x$period = apply(as.data.frame(x$date2), 1, function(x){
                findInterval(as.Date(x), periods)
            })

Answer 2

You can use dates in date1 to find intervals in date2

findInterval(x$date2, x$date1)
#[1] 0 1 2