CODEWITHSUNDEEP
rvector
René Nyffenegger
René Nyffenegger

Reputation: 40543

How do I create an empty vector of dates?

Is it possible to create an empty vector of dates in r?

I can create an empty vector of integers, doubles, logicals etc:

> integer()
integer(0)
> double()
numeric(0)
> logical()
logical(0)
> length(integer())
[1] 0

but this meme doesn't work for dates, as date() returns the current system date and time. So, how would I create an emtpy vector of dates?

Upvotes: 23

Views: 19209

Answers (4)

gbrunick
gbrunick

Reputation: 61

This appears to work and saves a few keystrokes relative to some of the other answers:

> as.Date(character(0))
Date of length 0

Upvotes: 2

Dylan S.
Dylan S.

Reputation: 389

Using the lubridate package and deciding what your intended format will be (eg. yyyy/mm/dd) you can use:

lubridate::ymd()
# or
lubridate::mdy()

etc.

Upvotes: 9

PAC
PAC

Reputation: 5366

With recent versions of R, you have to supply the origin : 

as.Date(x = integer(0), origin = "1970-01-01")

Upvotes: 20

IRTFM
IRTFM

Reputation: 263421

Just add a class attribute to a length-0 interger and it's a Date (at least it will appear to be one if you extend it with values that are sensible when interpreted as R-Dates):

>  x <- integer(0)
> x
integer(0)
> class(x) <- "Date"
> x
character(0)
> class(x)
[1] "Date"
> y <- c(x, 1400)
> y
[1] "1973-11-01"

The output from as.Date happens to be a character value so the first call is a bit misleading. 

> as.Date(integer())
character(0)
> str( as.Date(integer()) )
Class 'Date'  num(0) 
> dput( as.Date(integer()) )
structure(numeric(0), class = "Date")

Upvotes: 12

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