Omitting a certain time range from R difftime calculation

Question

I have data with start and end date-times in POSIXct format. I want to calculate the number of hours between each start and end date-time, omitting the hours between 11 pm and 5 am from the calculation. Here is the sample data:

times <- data.frame(start = c('2021-11-01 04:08:01 EDT', '2021-11-02 08:56:06 EDT', '2021-11-04 08:59:24 EDT', '2021-11-08 17:48:37 EST'), 
                    end = c('2021-11-01 23:44:01 EDT', '2021-11-03 11:04:01 EDT', '2021-11-05 13:25:08 EDT', '2021-11-12 04:56:03 EDT')) %>%
  mutate(start = as.POSIXct(start), 
         end = as.POSIXct(end))

How can I do this? I am not sure how to proceed.

Answer 1

A way could be:

times %>% rowwise() %>% 
  mutate( 
    hours = length(seq.POSIXt(start,end, "hour")),
    hours_not_11_17 = with(as.POSIXlt(seq.POSIXt(start,end, "hour")), 
                           length(which(!between(hour, 11, 17))))) %>%
  ungroup()

#   start               end                 hours hours_not_11_17
#   <dttm>              <dttm>              <int>           <int>
# 1 2021-11-01 04:08:01 2021-11-01 23:44:01    20              13
# 2 2021-11-02 08:56:06 2021-11-03 11:04:01    27              20
# 3 2021-11-04 08:59:24 2021-11-05 13:25:08    29              20
# 4 2021-11-08 17:48:37 2021-11-12 04:56:03    84              62