R help - Dec 2008 - Shrink Trellis margins settings (when printed to png file)

Dear R-experts,

I have two problems:

PROBLEM (1)
-----------

I want to produce a very small png file (35 x 18 px) that contains a
histogram without a figure region or margins, only the pure heights. 
In the base graphic system this is simple:

  png(filename = "hist.png", res = 72, width=35, height=18)
        par(mar=c(0,0,0,0), oma=c(0,0,0,0))
        hist(rnorm(100), main="")
  dev.off()

Now I want a grid graphics output as I need the graphic as an object.
I tried several trellis.par settings but I was not able to figure it out
(PROBLEM (1)).

Up to now it looks like this:

library(lattice)
histogram(rnorm(100), xlab="", ylab="", 
                     	 par.settings=list(
axis.line=list(col="transparent"),
xlab.text=list(col="transparent"),
ylab.text=list(col="transparent"),
	
axis.text=list(col="transparent"))
 )

This looks acceptable although I would like smaller margins, that is to say
no margins at all. How cab I achieve that?



PROBLEM (2) 
-----------
Now is, that when it is printed to the png file, the graphic almost consist
of margins only. The main part of the plot shrinks to some tiny points.

I don't know how to change the settings, so I that I get the same as in the
base system.

Does anyone know?


TIA
Mark

On Wed, Dec 17, 2008 at 8:11 AM, Mark Heckmann <mark.heckmann at gmx.de>
wrote:
> Dear R-experts,
>
> I have two problems:
>
> PROBLEM (1)
> -----------
>
> I want to produce a very small png file (35 x 18 px) that contains a
> histogram without a figure region or margins, only the pure heights.
> In the base graphic system this is simple:
>
>  png(filename = "hist.png", res = 72, width=35, height=18)
>        par(mar=c(0,0,0,0), oma=c(0,0,0,0))
>        hist(rnorm(100), main="")
>  dev.off()
>
> Now I want a grid graphics output as I need the graphic as an object.
> I tried several trellis.par settings but I was not able to figure it out
You could do it this way if you really want, but a better approach
would be to directly plot the pieces you want (rather than start with
a high-level solution and get rid of the pieces you don't want). For
example:


library(lattice)
library(grid)

x <- rnorm(100)
limits <- prepanel.default.histogram(x, breaks = NULL)
## grid.newpage() # to start a new page
pushViewport(viewport(xscale = extendrange(limits$xlim),
                      yscale = extendrange(limits$ylim)))
panel.histogram(x, breaks = NULL)


-Deepayan

> (PROBLEM (1)).
>
> Up to now it looks like this:
>
> library(lattice)
> histogram(rnorm(100), xlab="", ylab="",
>                         par.settings=list(
> axis.line=list(col="transparent"),
> xlab.text=list(col="transparent"),
> ylab.text=list(col="transparent"),
>
> axis.text=list(col="transparent"))
>  )
>
> This looks acceptable although I would like smaller margins, that is to say
> no margins at all. How cab I achieve that?
>
>
>
> PROBLEM (2)
> -----------
> Now is, that when it is printed to the png file, the graphic almost consist
> of margins only. The main part of the plot shrinks to some tiny points.
>
> I don't know how to change the settings, so I that I get the same as in
the
> base system.
>
> Does anyone know?
>
>
> TIA
> Mark
>
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