R help - Feb 2005 - basic question about changing limits on generated plots

Is it possible to change the limits on plots that are already on the
screen?  In particular, is there any R equivalent to the sequence of
matlab commands

plot(1:10,1:10)
hold on
plot(2:12,5:15)

I know I can use points and lines to add points and lines to plots,
but the limits of the plot do not change when I do this.

Looking at various examples, it seems that the answer is "no", but I
wanted to make sure.  This seems to make exploratory data analysis
somewhat more challenging.

It also seems like it would be plausible to write a package on top of
the standard graphics functions that keeps track of what you've done
and automatically replots.  Which makes me think, has someone already
done this?

Cheers,

rif

On Wed, 2005-02-23 at 17:42 -0500, rif wrote:
> Is it possible to change the limits on plots that are already on the
> screen?  In particular, is there any R equivalent to the sequence of
> matlab commands
> 
> plot(1:10,1:10)
> hold on
> plot(2:12,5:15)
> 
> I know I can use points and lines to add points and lines to plots,
> but the limits of the plot do not change when I do this.
> 
> Looking at various examples, it seems that the answer is "no",
but I
> wanted to make sure.  This seems to make exploratory data analysis
> somewhat more challenging.
> 
> It also seems like it would be plausible to write a package on top of
> the standard graphics functions that keeps track of what you've done
> and automatically replots.  Which makes me think, has someone already
> done this?
> 
> Cheers,
> 
> rif
I have not used Matlab, but I suspect that you want to use:

par(new = TRUE)

For example:
> plot(1:10,1:10)
# Check plot region limits
> par("usr")
[1]  0.64 10.36  0.64 10.36

# Set par("new") to not overwrite existing
plot
> par(new = TRUE)
> plot(2:12,5:15)
# Re-check plot region limits
> par("usr")
[1]  1.6 12.4  4.6 15.4

See ?par for more information.

Note also that par("usr") is not read-only, so you can explicitly
change
it when required:
> plot(1:10,1:10)
> par("usr")
[1]  0.64 10.36  0.64 10.36

# Now reset the plot region limits
> par(usr = c(0, 20, 0, 20))
# Check it
> par("usr")
[1]  0 20  0 20


You do not indicate what OS you are using, but Under Windows, there is
an ability to record plots. See R Windows FAQ 4.2. Otherwise, save the R
code that you use to generate the plot and either C&P it or source() it
or use ESS.

HTH,

Marc Schwartz