R help - May 2010 - Are there better ways to save and restore par() settings

Some of the help page examples use the form:

opar <- par(<something>)
     .....plotting activities...
par(opar)

This seems to "work" well, yet I have read in some places that it is  
not the preferred method to keep you parameters from getting  
corrupted. What is the preferred method?

A worked example from a recent posting with minor additions:

   opar <- par(mar=c(3,5,0,5))
        layout(rbind(c(4,1,1,5), c(2,2,3,3)), widths=c(1,1,1,1),
                           heights=c(.75,2.25))
           barplot(0,0, axes=FALSE)
             legend(x=0.5, y=0, legend=c("Example 1", "Example
2"),
                   pch=c(1,2), cex=1.5, xjust=1, yjust=0.5, bty="n")
         plot(1:10,1:10, pch=1)
         plot(1:20,1:20, pch=2)
  par(opar)

-- 
David Winsemius, MD
West Hartford, CT

On 14/05/2010 3:51 PM, David Winsemius wrote:
> Some of the help page examples use the form:
>
> opar <- par(<something>)
>      .....plotting activities...
> par(opar)
>
> This seems to "work" well, yet I have read in some places
Please include commented, retrievalbe citations for "some places".
> that it is  
> not the preferred method to keep you parameters from getting  
> corrupted. What is the preferred method?
>
>   
The above, with the restore wrapped in on.exit(), as your sources should 
have said.

Duncan Murdoch
> A worked example from a recent posting with minor additions:
>
>    opar <- par(mar=c(3,5,0,5))
>         layout(rbind(c(4,1,1,5), c(2,2,3,3)), widths=c(1,1,1,1),
>                            heights=c(.75,2.25))
>            barplot(0,0, axes=FALSE)
>              legend(x=0.5, y=0, legend=c("Example 1",
"Example 2"),
>                    pch=c(1,2), cex=1.5, xjust=1, yjust=0.5,
bty="n")
>          plot(1:10,1:10, pch=1)
>          plot(1:20,1:20, pch=2)
>   par(opar)
>
>