[R] Add points to subplots

[Greg Snow]

There is a subplot function in the TeachingDemos package, but its
purpose is to put a small plot somewhere inside of a large plot.  You
can use it to position 2 plots on a blank plot.  It does return the
information that you need to then go back and modify the individual
plots.  However, it does not work for a plotting function that itself
splits the plotting area into multiple plots (the split.screen option
will have the same problem).

If the function that you are running does "par(mfrow=c(2,1))"
internally then it will not play nicely with the other options.  If
the function just produces 2 plots and expects you to have run the par
command yourself (either mfrow or ask=TRUE, etc.) then you have more
options.  However if you use the split.screen functions then you will
need to have a way to call screen() before the 2nd plot.  The setHook
option may work for you there.

On Wed, Jun 18, 2014 at 10:15 AM, Luca Cerone <luca.cerone at gmail.com> wrote:
> Hi Greg and Jim.
> In the end I solved by modifying the function.
> I was just wondering if there is some function similar to Matlab's subplot,
> which let you change the active plot.
>
> Next time I will run in the same issue I will try the split.screen
> function proposed by Jim.
>
> Thanks a lot for the help,
> Cheers,
> Luca
>
> 2014-06-17 18:00 GMT+02:00 Greg Snow <538280 at gmail.com>:
>> I am not familiar with the pamr.plotcv function, but in general if it
>> uses par(mfrow=c(2,1)) to set up for the multiple plots then your
>> problem with going back to the first plot is that you have lost the
>> other information (such as user coordinates) needed to add to the 1st
>> plot.  You can see that with the following base graphics commands:
>>
>> par(mfrow=c(2,1))
>> plot(runif(25),rnorm(25))
>> tmp <- par(no.readonly=TRUE)
>> hist(rnorm(1000))
>>
>> par(mfg=c(1,1))
>> abline(h=0, col='red')
>>
>> The horizontal line is at what would be 0 in the lower plot, not the
>> upper.  Since I saved the graphics parameters I can do the correct
>> thing with a command like:
>>
>> par(mfg=c(1,1), plt=tmp$plt, usr=tmp$usr)
>> abline(h=0, col='blue')
>>
>> You can see the new line is in the correct place.
>>
>> Looking at the help for pamr.plotcv it does not look like it has any
>> nice built-in ways to save the plotting parameters (some functions
>> would let you plot just the top, edit, then plot just the bottom).
>> Bot there is a hook to the plot.new function that can let us work
>> around this.  Try the following:
>>
>> mypars <- list()
>> updatepars <- function() {
>> n <- length( .GlobalEnv$mypars )
>> .GlobalEnv$mypars[[ n + 1 ]] <- par(no.readonly=TRUE)
>> }
>> setHook('before.plot.new', updatepars)
>>
>> par(mfrow=c(2,1))
>> plot(runif(25),rnorm(25))
>> hist(rnorm(1000))
>>
>> setHook('before.plot.new',NULL, 'replace' ) ## clean up
>>
>> par( mfg=c(1,1), plt=mypars[[2]]$plt, usr=mypars[[2]]$usr )
>> abline( h=0, col='blue' )
>>
>>
>> This creates a global variable "mypars" that is an empty list (we
>> should really figure out a way without using the global, but my
>> current thoughts would make this much more complicated, any
>> suggestions are welcome).  Then it creates a small function that will
>> add the current results of 'par' to that list.  Then this function is
>> set as a hook to be run before 'plot.new' so that any new plot will
>> first save the previous parameter settings.  Now we run the plotting
>> commands and use the parameters that were saved into 'mypars'.  I
>> chose to save all the parameters from every old plot in case more than
>> what is shown is needed, this could be used to go back 3 or 4 plots if
>> more than just 2 are plotted.
>>
>> Try this with pamr.plotcv to see if it works (you may need to set some
>> additional parameters depending on what all pamr.plotcv does).
>>
>>
>> Whether this is the easy solution or not can be debated.  Hope it helps,
>>
>>
>>
>>
>> On Thu, Jun 12, 2014 at 9:06 AM, Luca Cerone <luca.cerone at gmail.com> wrote:
>>> Dear all,
>>> I am running some analysis using the pamr package (available on CRAN).
>>>
>>> One of the plots I produce is made using the function "pamr.plotcv".
>>> This displays two plots in the same figure (using par(mfrow=c(2,1)).
>>>
>>> When the figure is created, I would like to be able to add some points
>>> and lines, to the top plot.
>>>
>>> After producing the plot with pamr.cvplot, I have tried to add a line
>>> doing something like:
>>>
>>> par(mfg=c(1,1))
>>> lines(c(3,3), c(0,1), col = "blue", lty = 3)
>>>
>>> However this doesn't work and the line is shown in the bottom plot.
>>> How can I add points and lines to the top plot?
>>>
>>> Thanks a lot in advance for the help,
>>>
>>> Cheers,
>>> Luca
>>>
>>> ______________________________________________
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>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>>
>> --
>> Gregory (Greg) L. Snow Ph.D.
>> 538280 at gmail.com
>
>
>
> --
> Luca Cerone
>
> Tel: +34 692 06 71 28
> Skype: luca.cerone
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.



-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com