R - 日期格式检查

Question

I am trying to check whether a given date is in dd/mm/yyyy format or not in R language and also whether it is a valid date or not at the same time. I want output in TRUE or FALSE format, eg

Input :

date<- c('12/05/2016','35/11/2067','12/52/1000')

Output :

TRUE FALSE FALSE

Answer 1

You can use this function:

IsDate <- function(mydate, date.format = "%d/%m/%y") {
  tryCatch(!is.na(as.Date(mydate, date.format)),  
           error = function(err) {FALSE})  
}

IsDate(date)
[1]  TRUE FALSE FALSE

Original source of the code here .

.

Answer 2

you can also use lubridate package:

library(lubridate)
!is.na(parse_date_time(c('12/05/2016','35/11/2067','12/52/1000'),orders="dmy"))

Answer 3

Here is a vectorized base R function that handles NA , and is safe against SQL injection:

is_date = function(x, format = NULL) {
  formatted = try(as.Date(x, format), silent = TRUE)
  is_date = as.character(formatted) == x & !is.na(formatted)  # valid and identical to input
  is_date[is.na(x)] = NA  # Insert NA for NA in x
  return(is_date)
}

Let's try:

> is_date(c("2020-08-11", "2020-13-32", "2020-08-11; DROP * FROM table", NA), format = "%Y-%m-%d")
## TRUE FALSE FALSE    NA