as.Date() does not respect POSIXct time zones

Question

Okay so here is a subtle "quirk" in the r as.Date function converting from a POSIXct with a timezone, which I am wondering if it is a bug.

> as.POSIXct("2013-03-29", tz = "Europe/London")
[1] "2013-03-29 GMT"
> as.Date(as.POSIXct("2013-03-29", tz = "Europe/London"))
[1] "2013-03-29"

So far no problem, but.....

> as.POSIXct("2013-04-01", tz = "Europe/London")
[1] "2013-04-01 BST"
> as.Date(as.POSIXct("2013-04-01", tz = "Europe/London"))
[1] "2013-03-31"

Anybody seen this? Is this a bug or another quirk? April fools?

`Europe/Berlin` *doesn't* as well with `as.Date` goes back to March 31st. — Arun, Apr 01 '13 at 12:37
But this happens with `"2013-03-01"` as well. `as.Date` gives Feb 28th. — Arun, Apr 01 '13 at 12:39
so... we have a problem? Because I'm getting the same issue on OS/X. Both R2.15.2. Have come across other issues like this before with xts but this time xts is not loaded. — Thomas Browne, Apr 01 '13 at 12:39

score 8 · Accepted Answer · answered Apr 01 '13 at 12:44

8

The default time zone for as.Date.POSIXct is "UTC" (see the help page). Try as.Date(as.POSIXct("2013-04-01", tz = "Europe/London"),tz = "Europe/London").

answered Apr 01 '13 at 12:44

Roland

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aha! Guess I should have woken up later ;) – Thomas Browne Apr 01 '13 at 12:45

as.Date() does not respect POSIXct time zones

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