Checking if date is blank in R? -

an easy 1 sure knows how this...

in r, looking is.blank error trap in function user can specify date or can blank , default use today's date (i.e. sys.date())

i tried

date.end <- ""  # in function   if (date.end == "" || is.null(date.end)) {   message("end date not specified , setting today")   date.end <- sys.date() } else {   # use date.end passed in date class } 

but check freaks out chartodate(), i.e.

test.end == "" error in chartodate(x) :    character string not in standard unambiguous format 

please advise how 1 check blank dates in base r? (and other wisdom error trapping dates...)

adding clarify:

1. most times function dates, e.g.

   date.end <-  as.date("31/03/2015", "%d/%m/%y") 

   so not want change class.

2. however, how handle odd case want default today if user not specify date?

be aware sys.date() returns object of date class. see class(sys.date()). hence == comparison not make sense comparing character date.

one way solve problem convert date character:

date.end <- ""  # in function   if (date.end == "" || is.null(date.end)) {   message("end date not specified , setting today")   date.end = as.character(sys.date()) } ##end date not specified , setting today  date.end == "" ##[1] false  print(date.end) ##[1] "2015-04-01" 

note date.end character.

please see discussion in in post.

edit: complete overhaul. ok, reading follow-up comments , questions appears want following (although it's still not quite clear).

i think you're making more complicated is. first, let's make function can handle single (i) date, (ii) perhaps ill-formatted character, or (iii) null object.

datehandler <- function(x) {   if (is.null(x) || identical(x, "")) {     out <- sys.date()   } else {     x <- as.character(x)     out <- as.date(x, format = "%y-%m-%d")     if (is.na(out)) {       out <- sys.date()     }   }   return(out) }  # let's test in number of examples: datehandler("2014-02-21") datehandler(null) datehandler("21/03/1999") # wrong format, returns today datehandler("") datehandler("2014-04-01") datehandler(sys.date()) 

now, let's make function applies datehandler on list of dates:

handlelistofdates <- function(list.of.dates) {   return(do.call(c, lapply(list.of.dates, datehandler))) }  # let's test that: test.data.list <- list("2014-05-01", null, "", sys.date(),                         "2015-02-02", "1999-12-31", "") #print(test.data.list)  # see  handlelistofdates(test.data.list) # [1] "2014-05-01" "2015-04-01" "2015-04-01" "2015-04-01" "2015-02-02" "1999-12-31" "2015-04-01" 

the function handlelistofdates correctly handle vector instead of list of dates. hope want.