R help - Jun 2006 - Help with evaluation of expressions

Hello all: 

 

I have searched through the help files and I have been unsuccessful in
solving this problem.

 

I am trying to create a small wrapper function that will go around a
call to a plot function and create a windows metafile in the directory
and also write the name of the file to a text file. The purpose is to
efficiently bring a large number of plots into powerpoint.  I am using
platform      

 i386-pc-mingw32           

arch           i386                      

os             mingw32                   

system         i386, mingw32             

status                                   

major          2                         

minor          3.0                       

year           2006                      

month          04                        

day            24                        

svn rev        37909                     

language       R                         

version.string Version 2.3.0 (2006-04-24)

 

I would like the function to handle trellis plots as well as regular
plots.

 

Here is the function.

 

plotSlide<-function(pltexpr){

  expr<-as.expression(pltexpr)

  numslide<-length(dir(pattern="wmf"))+1

  fname<-paste("SG",numslide,".wmf",sep="")

  dirlist<-dir(pattern="SlideList.txt")

  if (length(dirlist)==1){

    fs<-file("SlideList.txt",open="at")

    write(paste(fname,"Graph",sep=","),file=fs)

    close(fs)} else {

   
write(paste(fname,"Graph",sep=","),file="SlideList.txt")

    }

 # if(is.element(class(eval(expr)),"trellis")){

 #   trellis.device(device = win.metafile, theme = "col.whitebg", new
TRUE, retain = FALSE, file=fname,width=6,height=4)

 #   print(eval(expr))

 #  dev.off()

 #   return(fname)

 #   } 

   win.metafile(file=fname,width=6,height=4)

   print(dev.cur())

  eval(expr)

  dev.off()

  return(fname)

 }

 

The function as displayed will write the regular graphics.  If I
uncomment the commented lines it will write trellis graphics but will no
longer write the regular graphics. (I get a bunch of empty graphs - the
graph frame but no data).  So it appears that when I evaluate the
expression to see if it is a trellis graph it no longer correctly
evaluates at the end of the function.  Any advice would be most welcome.

 

Michael Conklin

Chief Methodologist - Advanced Analytics

 

MarketTools, Inc.

6465 Wayzata Blvd. Suite 170

Minneapolis, MN 55426

Tel: 952.417.4719 | Mobile:612.201.8978

Michael.Conklin@markettools.com <mailto:Michael.Conklin@markettools.com>


 

MarketTools(r)    http://www.markettools.com
<http://www.markettools.com/> 

 

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Michael Conklin <michael.conklin <at> markettools.com> writes:
> 
> I have searched through the help files and I have been unsuccessful in
> solving this problem.
> 
> I am trying to create a small wrapper function that will go around a
> call to a plot function and create a windows metafile in the directory
> and also write the name of the file to a text file. The purpose is to
> efficiently bring a large number of plots into powerpoint.  I am using
> platform      
Try this variant. Note that I am using emf instead of wmf, it's a bit more
stable. And I had to prepare an undecorated filename since savePlot has special
ideas about appending appendixes. 

Please, if you post, provide a full working demo example next time, not only the
function. There are only few genius who can see the right way without firing up
the gui.

Dieter
------

plotSlide<-function(pltexpr){
  expr<-as.expression(pltexpr)
  numslide<-length(dir(pattern="emf"))+1
  fname0<-paste("SG",numslide,sep="")
  fname<-paste(fname0,".emf",sep="")
  dirlist<-dir(pattern="SlideList.txt")
  if (length(dirlist)==1){
    fs<-file("SlideList.txt",open="at")
    write(paste(fname,"Graph",sep=","),file=fs)
    close(fs)} else {
   
write(paste(fname,"Graph",sep=","),file="SlideList.txt")
    }
  p=eval(pltexpr)
  if (is.null(p)) {
    savePlot(fname0,type="emf")
  } else {
    trellis.device(device = win.metafile, theme = "col.whitebg", new
TRUE, retain = FALSE, file=fname,width=6,height=4)
    print(p)
  }
  dev.off()
  fname
}

plotSlide(
  plot(rnorm(100))
)

library(lattice)
plotSlide(
  xyplot(Sepal.Length  ~ Petal.Length, data = iris)
)