[Rd] strange behavior from cex="*"

[Kevin R. Coombes]

Hi Ben,

Just a few things to add.

First, the same phenomenon occurs when you use any character string as 
the value of cex; there is nothing special about "*".

Second, you cannot get this phenomenon by trying to do something like
     par(cex="*")
because the par function actually checks if the value is a nonnegative 
number.

Finally, producing the different graphs is clearly occuring inside the 
"plot.xy" function, although I have not yet caused R2.14 to hang. This 
at least suggests a fix: make sure that plot.xy checks the type of the 
cex argument in the same way that par does.

     Kevin

#######################
  xy <- xy.coords(1:10, 1:10)
  plot(xy)
  for(i in seq(100)) plot.xy(xy, "p", cex="*", col=i)
#######################

 > sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: x86_64-pc-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] png_0.1-3

loaded via a namespace (and not attached):
[1] tools_2.14.0


On 11/16/2011 3:38 PM, 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.
>
>     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
>
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