How to Check If a Column Is a Date in R

Is there a way to check if a column is a Date in R?

You could try to coerce all the columns to as.Date and see which ones succeed. You would need to specify the format you expect dates to be in though. E.g.:

data <- data.frame(
  Date=c("10/11/2012","10/12/2012"),
  AE=c(1211,100),
  Percent=c(0.03,0.43)
)

sapply(data, function(x) !all(is.na(as.Date(as.character(x),format="%d/%m/%Y"))))
#Date      AE Percent 
#TRUE   FALSE   FALSE 

In R how to calculate if Date is earlier then date X?

You can use pmax:

DF$Beginning_2 <- pmax(DF$Beginning, as.Date("2020-01-01"))
#DF$Beginning_2 <- pmax(DF$Beginning, "2020-01-01") #Works also

DF
#   Beginning        End Beginning_2
#1 2020-12-31 2021-01-12  2020-12-31
#2 2018-01-02 2020-03-10  2020-01-01
#3 2019-04-12 2020-12-04  2020-01-01
#4 2020-10-15 2021-03-27  2020-10-15

str(DF)
#'data.frame':   4 obs. of  3 variables:
# $ Beginning  : Date, format: "2020-12-31" "2018-01-02" ...
# $ End        : Date, format: "2021-01-12" "2020-03-10" ...
# $ Beginning_2: Date, format: "2020-12-31" "2020-01-01" ...

How to validate date in R

Simple way:

d <- try(as.Date(date, format="%d-%m-%Y %H:%M:%S"))
if("try-error" %in% class(d) || is.na(d)) {
  print("That wasn't correct!")
}

Explanation: format.Date uses as.Date internally to convert date into an object of the Date class. However, it does not use a format option, so as.Date uses the default format, which is %Y-%m-%dand then %Y/%m/%d.

The format option from format.Date is used only for the output, not for the parsing. Quoting from the as.Date man page:

The ‘as.Date’ methods accept character strings, factors, logical
‘NA’ and objects of classes ‘"POSIXlt"’ and ‘"POSIXct"’. (The
last is converted to days by ignoring the time after midnight in
the representation of the time in specified timezone, default
UTC.) Also objects of class ‘"date"’ (from package ‘date’) and
‘"dates"’ (from package ‘chron’). Character strings are processed
as far as necessary for the format specified: any trailing
characters are ignored.

However, when you directly call as.Date with a format specification, nothing else will be allowed than what fits your format.

See also: ?as.Date

R - Date format check

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.

.

R: Check if a date is valid

Sure. Just try to parse it:

R> days <- 28:31
R> dates <- paste0("2020-02-", days)
R> as.Date(dates)
[1] "2020-02-28" "2020-02-29" NA           NA          
R> 

This shows that in 2020, Feb 28 and 29 existed (leap year) but not 30 and 31.

From you three vectors you could use sprintf("%4d-%02d-%02", y, m, d) to create a vector of text inputs to parse.

Find date columns in R. Date column have different date-formats. Replace all date format to dd-mmm-yyyy

Using the tidyverse(see Note):

    date_parser <- function(column){
   if(any(grepl("[-]",column))){

 format(parse_date_time(column,orders = c("dmy","dby","ymd")),"%d-%b-%Y")
     }

   else column
 }
   df %>% 
   mutate_at(-1,~ stringr::str_replace_all(.,"\\/","-")) %>% 
  purrr::map_dfr(~date_parser(.))
# A tibble: 3 x 5
  Name  Col2        col3        Col4  col5       
  <chr> <chr>       <chr>       <chr> <chr>      
1 A     01-Jan-2020 05-Feb-2020 XYZ   01-Mar-2020
2 B     01-Feb-2020 13-Apr-2020 REW   01-Jan-2019
3 C     31-May-2020 17-Sep-2020 RRRR  12-Jan-2020

NOTE:

This is not an actual date, you can convert it again with lubridate although I doubt dttm supports mixed dates. Hence as far as I know, you'll still resort to characters.

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