I have a data frame as follows with a Session end time (%D/%M/%Y %H:%M:%S) and Session Duration (%M:%S). I want to obtain the Session start time in the format %D/%M/%Y %H:%M, by subtracting the Session Duration from the Session End time and attaching it to the data frame as a separate column called "SessionEnd".
How am I supposed to do this in R?
SessionEnd <- c("22/06/2022 0:01:00", "22/06/2022 0:09:00", "22/06/2022 0:10:00", "22/06/2022 0:11:00", "22/06/2022 0:14:00")
Session_Duration <- c("6:11", "8:22", "9:59", "8:09", "4:55")
df <- data.frame(SessionEnd, Session_Duration)
The output should look like the one below.
| Session_End | Session_Duration | Session_Start |
|---|---|---|
| 22/06/2022 0:01:00 | 6:11 | 21/06/2022 23:54:49 |
| 22/06/2022 0:09:00 | 8:22 | 22/06/2022 00:00:38 |
| 22/06/2022 0:10:00 | 9:59 | 22/06/2022 00:00:01 |
| 22/06/2022 0:11:00 | 8:09 | 22/06/2022 00:02:51 |
| 22/06/2022 0:14:00 | 4:55 | 22/06/2022 00:09:05 |
>Solution :
It would be easy to do this with functions from lubridate package –
library(dplyr)
library(lubridate)
df %>%
mutate(SessionEnd = dmy_hms(SessionEnd),
Session_Duration = ms(Session_Duration),
SessionStart = SessionEnd - Session_Duration) #%>%
#If you want to maintain the same format as input add the below line
#mutate(across(c(SessionEnd, SessionStart), format, '%d/%m/%Y %H:%M:%S'))
# SessionEnd Session_Duration SessionStart
#1 2022-06-22 00:01:00 6M 11S 2022-06-21 23:54:49
#2 2022-06-22 00:09:00 8M 22S 2022-06-22 00:00:38
#3 2022-06-22 00:10:00 9M 59S 2022-06-22 00:00:01
#4 2022-06-22 00:11:00 8M 9S 2022-06-22 00:02:51
#5 2022-06-22 00:14:00 4M 55S 2022-06-22 00:09:05