Loop to measure difference in time between two values

Question

Im trying to calculate the occupancy rate in rooms per hour, I want to do this by checking how many minutes in an hour a room is occupied. Occupancy time is when column 'occupied' is 1 and change to 0. I have succeeded in calculating the occupancy minutes by using:

Timediff <- Test %>% arrange(Date_Time)%>% mutate(difftime= difftime(lead(Date_Time),Date_Time, units = "mins"))

And my table looks like this now:

So what I have in mind is this: To calculate the occupancy rate per hour, I'm adding all the occupied time (difftime for every 'occupied = 1') in that hour, divide it by 60, times 100%.

Example:

July 30th 2017:

Occupancy rate from 11.00 till 12.00 (11.59) = (14+1)/60*100%

12.00 till 13.00 (12.59) = (14+5)/60*100%

13.00 till 14.00 (13.59) = (11+14)/60*100%

Etc. etc.

How can I do this?

Answer 1

Considering that your picture represents one "room" then, you just want to use diff(yourdata$Date_Time) and you will have a vector of occupiedtime; not occupiedtime; etc.

Answer 2

You can use the lag function instead of a loop.

library(dplyr)

df = df %>% 
    mutate(Date_Time_diff = difftime(Date_Time, lag(Date_Time), units = 'mins'))