How to convert date and time into a numeric value in R

Question

I am relatively new to R and I have a dataset in which I am trying to convert a date and time into a numeric value. The date and time are in the format 01JUN17:00:00:00 under a variable called pickup_datetime. I have tried using the code

cab_small_sample$pickup_datetime <- as.numeric(as.Date(cab_small_sample$pickup_datetime, format = '%d%b%y'))

but this way doesn't incorporate time, I tried to add the time format to the format section of code but still did not work. Is there an R function that will convert the data into a numeric value>

Answer 1

R has two main time classes: "Date" and "POSIXct". POSIXct is a datetime class and you can get all the gory details at: ? DateTimeClasses ? DateTimeClasses . The help page for the formats used at the time of data input, however, are at ?striptime .

cab_small_sample <- data.frame(pickup_datetime = "01JUN17:00:00:00")
cab_small_sample$pickup_dt <- as.numeric(as.POSIXct(cab_small_sample$pickup_datetime,
                                                        format = '%d%b%y:%H:%M:%S'))
 cab_small_sample
#   pickup_datetime pickup_dt
#1 01JUN17:00:00:00   1496300400  # seconds since 1970-01-01

I find that a "destructive reassignment of values" is generally a bad idea so as a "my (best?) practice rule" I don't assign to the same column until I'm sure I have the code working properly. (And I always leave an untouched copy somewhere safe.)

Answer 2

lubridate is an extremely handy package for dealing with dates. It includes a variety of functions which do the date/time parsing for you, as long as you can provide the order of components. In this case, since your data is in day-month-year-hms form, you can use the dmy_hms function.

library(lubridate)
cab_small_sample <- dplyr::tibble(
    pickup_datetime = c("01JUN17:00:00:00", "01JUN17:11:00:00"))
cab_small_sample$pickup_POSIX <- dmy_hms(cab_small_sample$pickup_datetime)