[R] png inside loop

[Joshua Wiley]

Dear Sacha,



On Mon, Mar 7, 2011 at 9:28 AM, Sacha Viquerat <tweedie-d at web.de> wrote:
> hello list! I'm sorry, I just stumbled over this strange behaviour (at least
> I am not able to explain the behaviour, therefore I assume it to be a
> strange behaviour):
>
> attach(water) # I know, this is not recommended
not only not recommended, not needed.  xyplot() has a data argument
you could have used.

>
> names(water[3:10])
> [1] "temp" "pH"   "DO"   "BOD"  "COD"  "no3"  "no2"  "po4"
>
> for (i in names(water)[3:10]){
>    fname<-paste("Henni/GFX/fem",i,".png",sep="")
>    mname<-paste("Henni/GFX/mal",i,".png",sep="")
>    png(fname,1000,1000)
>    xyplot(N_female~eval(parse(text=i)) |group,xlab=i,ylab="Abundance")
>    graphics.off()
>    png(mname,1000,1000)
>    xyplot(N_male~eval(parse(text=i)) |group,xlab=i,ylab="Abundance")
>    graphics.off()
> }
>
> well, to anyone's surprise, there are no plots in the folder. the loop
> finishes (i, fname and mname have values assigned) and executing
>
> png(fname,1000,1000)
> xyplot(N_female~eval(parse(text=i)) |group,xlab=i,ylab="Abundance")
> graphics.off()
>
> does produce a png in the folder. I assume this to be caused by the png

No.

> function, since removing the graphics.off() and playing with dev.off() and

I always thought using dev.off() was the "normal" way, but it may just
be *my* normal way.

> the likes did not help. anyone ideas?? am I missing the obvious??

It is obvious only insofar as it is noted in the FAQ.  Here is a link:
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-do-lattice_002ftrellis-graphics-not-work_003f

short answer, wrap your call in print() like so: print(xyplot(yourargument))

HTH,

Josh

>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/