From ripley@stats.ox.ac.uk  Tue Jul  2 20:11:28 2002
From: ripley@stats.ox.ac.uk (ripley@stats.ox.ac.uk)
Date: Tue, 2 Jul 2002 20:11:28 +0100 (BST)
Subject: POSIX formats have problems with NA (PR#1732)
In-Reply-To: <200207021851.UAA02822@pubhealth.ku.dk>
Message-ID: <Pine.LNX.4.31.0207022007520.27769-100000@gannet.stats>

This feature request is already implemented in R-devel.

It is not a bug, as why should logical NA be convertible to any other
format?

On Tue, 2 Jul 2002 oehl_list@gmx.de wrote:

>
> # pure replication code at end
>
> > # These work
> >
> > Sys.time() + NA
> [1] NA
> > as.POSIXlt(Sys.time(), "GMT") + NA
> [1] NA
> >
> > class(Sys.time() + NA)
> [1] "POSIXt"  "POSIXct"
> > class(as.POSIXlt(Sys.time(), "GMT") + NA)
> [1] "POSIXt"  "POSIXct"
> >
> > x <- Sys.time() + NA
> > y <- as.POSIXlt(Sys.time(), "GMT") + NA
> >
> > is.na(x)
> [1] TRUE
> > is.na(y)
> [1] TRUE
> >
> > x <- NA
> > class(x) <-  c("POSIXt", "POSIXct")
> > is.na(x)
> [1] TRUE
> >
> > # but these fail
> >
> > is.na(x) <- TRUE
> Error in as.POSIXct.default(value) : Don't know how to convert `value' to
> class "POSIXct"
> > is.na(y) <- TRUE
> Error in as.POSIXct.default(value) : Don't know how to convert `value' to
> class "POSIXct"
> >
> > x[] <- NA
> Error in as.POSIXct.default(value) : Don't know how to convert `value' to
> class "POSIXct"
> > y[] <- NA
> Error in as.POSIXct.default(value) : Don't know how to convert `value' to
> class "POSIXct"
> >
> > as.POSIXlt(NA)
> Error in as.POSIXlt(NA) : Don't know how to convert `NA' to class "POSIXlt"
> > as.POSIXct(NA)
> Error in as.POSIXct.default(NA) : Don't know how to convert `NA' to class
> "POSIXct"
>
>
>
>
> # These work
>
> Sys.time() + NA
> as.POSIXlt(Sys.time(), "GMT") + NA
>
> class(Sys.time() + NA)
> class(as.POSIXlt(Sys.time(), "GMT") + NA)
>
> x <- Sys.time() + NA
> y <- as.POSIXlt(Sys.time(), "GMT") + NA
>
> is.na(x)
> is.na(y)
>
> x <- NA
> class(x) <-  c("POSIXt", "POSIXct")
> is.na(x)
>
> # but these fail
>
> is.na(x) <- TRUE
> is.na(y) <- TRUE
>
> x[] <- NA
> y[] <- NA
>
> as.POSIXlt(NA)
> as.POSIXct(NA)
>
>
>
> --please do not edit the information below--
>
> Version:
>  platform = i386-pc-mingw32
>  arch = i386
>  os = mingw32
>  system = i386, mingw32
>  status =
>  major = 1
>  minor = 5.1
>  year = 2002
>  month = 06
>  day = 17
>  language = R
>
> Windows 2000 Professional (build 2195) Service Pack 1.0
>
> Search Path:
>  .GlobalEnv, package:ctest, Autoloads, package:base
>
> --
>
>
>
>
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-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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POSIX formats have problems with NA (PR#1732)
ripley@stats.ox.ac.uk