On Nov 16, 2011, at 22:38 , Ben Bolker wrote:
> Someone inquired on StackOverflow about apparently non-deterministic
> graphics behaviour in R. I noticed that they were using cex="*" and
> discovered some potentially weird behavior.
It can be reproduced much more simply (well, not the hang, but bad enough):
In a plain R application console (OSX Snow Leopard),
for (i in 1:100) plot(1:10,cex="*")
will _sometimes_ show big circles, indicating random data being picked up.
The "cex" is by definition numeric, so you can't expect to be able to pass a
character string, but the code should check.
>
> On repeated runs of the same code I can get different PNGs. If I set
> the number of runs high enough, I seem to be able to get R to hang.
> If I do a single version plotting to an interactive graphics window I
> can get the point sizes to jump around as I resize the window (someone
> reported being able to reproduce that behaviour in the Windows GUI as well).
>
> This is clearly a user error, but non-deterministic behaviour (and
> hanging) are a little disturbing.
>
> I haven't had a chance yet to try to dig in and see what's happening
> but thought I would report to see if anyone else could reproduce/figure
> it out.
>
> Ben Bolker
>
>
> ########################
> ## n <- 100 ## hangs R
>
> n <- 33
>
> fn <- paste("tmp",seq(n),"png",sep=".")
> for (i in seq(n)) {
> png(fn[i])
> plot(1:10,1:10,cex="*");
> dev.off()
> }
>
> ff <- subset(file.info(fn),select=size)
> ff <- ff[!duplicated(ff$size),,drop=FALSE]
> table(ff$size)
> require(png)
> pngs <- lapply(rownames(ff),readPNG)
>
> png.to.img <- function(x) matrix(rgb(x[,,1],x[,,2],x[,,3]),
> nrow=dim(x)[1],ncol=dim(x)[2])
>
> imgs <- lapply(pngs,png.to.img)
>
> par(mfrow=c(2,2))
> lapply(imgs,function(x) {
> plot(0:1,0:1,type="n",ann=FALSE,axes=FALSE)
> rasterImage(x,0,0,1,1)
> })
>
> #########################
>
>> sessionInfo()
> R Under development (unstable) (2011-10-06 r57181)
> Platform: i686-pc-linux-gnu (32-bit)
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> other attached packages:
> [1] glmmADMB_0.6.5 MASS_7.3-14 png_0.1-3
>
> loaded via a namespace (and not attached):
> [1] grid_2.15.0 lattice_0.19-33 nlme_3.1-102 tools_2.15.0
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
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