R / lubridate: Calculate number of overlapping days between two periods

Question

I am trying to calculate the number of overlapping days between two time periods. One period is fixed in a start and end date, the other is recorded as start and end dates i

Answer 1

I think you may be running into issues with max and min vs pmax and pmin:

library(dplyr)

df %>%
  mutate(overlap = pmax(pmin(my.end, end) - pmax(my.start, start) + 1,0))

       start        end overlap
1 2018-07-15 2018-07-20  0 days
2 2018-07-20 2018-08-05  5 days
3 2018-08-15 2018-08-19  5 days
4 2018-08-20 2018-09-15 12 days
5 2018-09-01 2018-09-15  0 days