Question

I want to create an if statement if the string cannot be converted to date, like the one below:

as.Date("2010-00-01")

But running the line above just keep giving the error output below:

Error in charToDate(x) : 
  character string is not in a standard unambiguous format

Which I cannot use it for if statement, how can I use a if statement if the string cannot be converted to date? Thanks.

Answer 1

Provide the format arg so it won’t be ambiguous. Bad dates are then always turned into NA.

d <- as.Date("2010-01-31", format="%Y-%m-%d") # OK
is.na(d) # FALSE

d <- as.Date("2010-00-31", format="%Y-%m-%d") # NA
is.na(d) # TRUE