formatting dates with R and as.date

Question

I'm trying to format dates with R. Can someone explain why R gives an error when these two strings are the exact same format? I cannot figure out how to manage these date strings, and any help is greatly appreciated as I'm new working with R.

> as.Date("09/18/2016 1:00 PM EDT")
Error in charToDate(x) : 
  character string is not in a standard unambiguous format
> as.Date("09/08/2016 8:30 PM EDT")
[1] "0009-08-20"

bad  <- as.Date("09/18/2016 1:00 PM EDT")
good <- as.Date("09/08/2016 8:30 PM EDT")

The 2nd conversion was also wrong -- it says the year is 9 AD. The easiest way to deal with dates is to use `lubridate`. — Hack-R, Sep 12 '16 at 21:52
You need to specify the format, see `?as.Date`. E.g: `as.Date(dates, format = "%m/%d/%y")` — Jaap, Sep 12 '16 at 21:52

score 2 · Answer 1 · answered Sep 12 '16 at 21:52

2

You missed the fact (and warning) that a non-standard format needs a format string for as.Date(). And you also want strptime() if you want parse hours/minutes etc:

R> strptime("09/18/2016 1:00 PM EDT", "%m/%d/%Y %I:%M %p")
[1] "2016-09-18 13:00:00 CDT"
R>

answered Sep 12 '16 at 21:52

Dirk Eddelbuettel

360,940
56
644
725

Glad to hear that. In that case please consider _accepting_ (click on tickmark only you see) and/or _upvoting_ (click on upwards facing triangle). That's how StackOverflow works... – Dirk Eddelbuettel Sep 13 '16 at 19:55
I don't have enough rep yet, but I will – MostlyRquestions Sep 16 '16 at 20:13
You should always be able to accept an answer to the question you posed. But yes, per http://stackoverflow.com/help/privileges you cannot yet upvote. – Dirk Eddelbuettel Sep 16 '16 at 20:27

formatting dates with R and as.date

1 Answers1