warning on gamma option in par(args) or calling par(= new)?

Dear All,

I have the following function

tstpar <-
 function(n = 200, want.pdf = FALSE, pdfFileName = NULL){
   oldpar <- par(no.readonly = TRUE)
   on.exit(par(oldpar))
   steps  <- seq(from = 1, to = 8, by = 1)
   h <- 10; w <- 6
   if(want.pdf){pdf(file = pdfFileName, onefile = TRUE,
   paper = "letter", width = w, height = h)}
   par(mfrow = c(4,2))
   for(i in steps){
     txt <- paste("i = ", i)
     hist(rnorm(n), main = txt)
   }
   if(want.pdf){dev.off()}
 }

when called with default values tstpar() every thing works fine.
However I get 2 sorts of warnings
1- if I call the function to generate a pdf as
  tstpar(want.pdf = TRUE, pdfFilename = "jj.pdf")
  I get the following warning msg:
  calling par(new=) with no plot in: par(oldpar)
  with an empty device which I don not understand since I close
  the device in the function.
2- If I comment the line
  if (want.pdf){dev.off()}
  I get the following warning
  'gamma' cannot be modified on this device in: par(args)
  with 2 empty devices.

I do not understand why I get those warnings and why I get those empty devices.
I looked up in RSiteSearch and I found the 2 following posts
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/38553.html
In this post M. Schwarz explains that there is not a plot created that's why R generates the
warning. In the case of tstpar, I generate the hist plots and should not be getting the warning.

And in the following post Prof Ripley refers to an old R warning for pdf() devices
Which is not the case here.
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/23215.html

I do not see what I am missing. Thanks for any hint.
I use R 2.5.1 under Win XP.
I apologize if the question is related to my older R version which I will upgrade.

AA.

	[[alternative HTML version deleted]]

You are calling par() *before* opening  and (in on.exit) *after* closing 
the pdf() device.  par() applies on a per-device basis, and if no device 
is open the default device will be opened.

As for why you get the warnings about 'gamma' and 'new', see ?par and read 
their entries.  Since you don't change any pars, I do not see why you are 
attempting to reset them.


On Thu, 27 Dec 2007, AA wrote:

Dear All,

I have the following function

tstpar <-
 function(n = 200, want.pdf = FALSE, pdfFileName = NULL){
   oldpar <- par(no.readonly = TRUE)
   on.exit(par(oldpar))
   steps  <- seq(from = 1, to = 8, by = 1)
   h <- 10; w <- 6
   if(want.pdf){pdf(file = pdfFileName, onefile = TRUE,
   paper = "letter", width = w, height = h)}
   par(mfrow = c(4,2))
   for(i in steps){
     txt <- paste("i = ", i)
     hist(rnorm(n), main = txt)
   }
   if(want.pdf){dev.off()}
 }

when called with default values tstpar() every thing works fine.
However I get 2 sorts of warnings
1- if I call the function to generate a pdf as
  tstpar(want.pdf = TRUE, pdfFilename = "jj.pdf")
  I get the following warning msg:
  calling par(new=) with no plot in: par(oldpar)
  with an empty device which I don not understand since I close
  the device in the function.
2- If I comment the line
  if (want.pdf){dev.off()}
  I get the following warning
  'gamma' cannot be modified on this device in: par(args)
  with 2 empty devices.

I do not understand why I get those warnings and why I get those empty 
devices.
I looked up in RSiteSearch and I found the 2 following posts
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/38553.html
In this post M. Schwarz explains that there is not a plot created that's 
why R generates the
warning. In the case of tstpar, I generate the hist plots and should not 
be getting the warning.

And in the following post Prof Ripley refers to an old R warning for 
pdf() devices
Which is not the case here.
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/23215.html

I do not see what I am missing. Thanks for any hint.
I use R 2.5.1 under Win XP.
I apologize if the question is related to my older R version which I will 
upgrade.

AA.

[[alternative HTML version deleted]]

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595