Full_Name: Jari Oksanen
Version: 2.6.2 RC (2008-02-07 r44369)
OS: Linux
Submission from: (NULL) (130.231.102.145)
Even if function xspline() is called with argument draw=FALSE, it requires a
graphics device (that it won't use since it was draw=FALSE). I run into this
because I intended to use xspline within a function (that does not yet draw:
there is plot method for that), and the function failed when called in a virgin
environment.
Here is an example in a virgin environemt just after starting R:
> out <- xspline(c(0,1,0), c(1,0,1), draw=FALSE)
Error in xspline(c(0, 1, 0), c(1, 0, 1), draw = FALSE) :
plot.new has not been called yet
> str(out)
Error in str(out) : object "out" not found
This works:
> plot(0)
> out <- xspline(c(0,1,0), c(1,0,1), draw=FALSE)
> str(out)
List of 2
$ x: num [1:3] 0 1 0
$ y: num [1:3] 1 0 1
This won't:
> dev.off()
null device
1
> xspline(c(0,1,0), c(1,0,1), draw=FALSE)
Error in xspline(c(0, 1, 0), c(1, 0, 1), draw = FALSE) :
plot.new has not been called yet
R graphics internal are black magic to me. However, it seems that the error
messge comes from function GCheckState(DevDesc *dd) in graphics.c, which is
called by do_xspline(SEXP call, SEXP op, SEXP args, SEXP env) in plot.c even
when xspline was called with draw = FALSE (and even before getting the argument
draw into do_xspline). It seems that graphics device is needed somewhere even
with draw = FALSE, since moving the GCheckState() test after findig the value
draw, and executing the test only if draw=TRUE gave NaN as the numeric output.
If this is documented behaviour, the documentation escaped my attention and beg
for pardon. It may be useful to add a comment on the help page saying that an
open graphics device is needed even when unused with draw=FALSE.
Cheers, Jari Oksanen
platform = i686-pc-linux-gnu
arch = i686
os = linux-gnu
system = i686, linux-gnu
status = RC
major = 2
minor = 6.2
year = 2008
month = 02
day = 07
svn rev = 44369
language = R
version.string = R version 2.6.2 RC (2008-02-07 r44369)
Locale:
LC_CTYPE=en_GB.UTF-8;LC_NUMERIC=C;LC_TIME=en_GB.UTF-8;LC_COLLATE=en_GB.UTF-8;LC_MONETARY=en_GB.UTF-8;LC_MESSAGES=en_GB.UTF-8;LC_PAPER=en_GB.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_GB.UTF-8;LC_IDENTIFICATION=C
Search Path:
.GlobalEnv, package:stats, package:graphics, package:grDevices, package:utils,
package:datasets, package:methods, Autoloads, package:base
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