R help - Mar 2011 - retrieve x y coordinates of points in current plot

Dear list,

is it somehow possible to retrieve the x and y coordinates of points in 
a scatterplot after it has been plotted? identify() somehow seems to 
manage this, so I was wondering whether it is possible?

I am asking as I wrote a function that identifies points inside a 
polygon and I would like it to work without supplying the x and y 
coordinates again but by retrieving them from the device.


Cheers
Jannis

jannis-2 wrote:
> 
> 
> is it somehow possible to retrieve the x and y coordinates of points in 
> a scatterplot after it has been plotted? identify() somehow seems to 
> manage this, so I was wondering whether it is possible?
> 
locator might be the more basic function you are looking for.

Dieter


--
View this message in context:
http://r.789695.n4.nabble.com/retrieve-x-y-coordinates-of-points-in-current-plot-tp3335642p3335692.html
Sent from the R help mailing list archive at Nabble.com.

Thanks for your replies, Dieter and Richard. I am aware of these two 
functions. I wanted, however, to write a similar function to identify by 
selecting large clouds of points. For this I would need to rertrieve 
their coordinates after the plot was called and created. As identify() 
is able to do this, I was wondering whether my function could do this as 
well in a similar manner. Until now, I have to supply the x and y 
coordinates to my function as well. I would like to avoid this.


Jannis

On 03/04/2011 06:55 PM, Dieter Menne wrote:
> jannis-2 wrote:
>>
>> is it somehow possible to retrieve the x and y coordinates of points in
>> a scatterplot after it has been plotted? identify() somehow seems to
>> manage this, so I was wondering whether it is possible?
>>
> locator might be the more basic function you are looking for.
>
> Dieter
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/retrieve-x-y-coordinates-of-points-in-current-plot-tp3335642p3335692.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>

If you want to identify the coordinates of points within a region, you 
might want to look at the ImageJ application.

http://rsbweb.nih.gov/ij/

IIRC it has some macros to find and classify spots.