How to check if a string is in datetime format in R?

Question

Edit: Is it possible to check if the string is in a certain format such as 'y-m-d','h:m:s'

Answer 1

lubridate::is.timepoint(Sys.time())
#> TRUE
lubridate::is.timepoint(Sys.Date())
#> TRUE

From the documentation of ?lubridate::is.timepoint:

TRUE if x is a POSIXct, POSIXlt, or Date object, FALSE otherwise.

---

If you want to identify only datetimes and not dates:

lubridate::is.POSIXt(Sys.time())
#> TRUE
lubridate::is.POSIXt(Sys.Date())
#> FALSE

---

EDIT.

If you want to check a specific format you can try to read it with that format, if you get NA, then it is not.

For example:

is.ymd_hms <- function(x) !is.na(lubridate::ymd_hms(x, quiet = TRUE))

is.ymd_hms("2020-01-01 22:22:22")
#> TRUE
is.ymd_hms("2020-31-01 22:22:22")
#> FALSE

Without lubridate:

is.ymd_hms2 <- function(x) !is.na(as.Date(x, "%Y-%m-%d %H:%M:%S"))

is.ymd_hms2("2020-01-01 22:22:22")
#> TRUE
is.ymd_hms2("2020-31-01 22:22:22")
#> FALSE

However, lubridate gives you more flexibility. Like:

is.ymd_hms("2020/01/01 22:22:22")
#> TRUE
is.ymd_hms2("2020/01/01 22:22:22")
#> FALSE