[R] Select.spatial on spplots

[cls59]

Julius Tesoro wrote:
> 
> Hi everyone. I posted this on R-sig-geo but got no response. 
> 
>  
> Can select.spatial() be used in an existing spplot? I have tried selecting
> points (eq) from a plot generated from sp. However, when I invoke
> select.spatial(eq). It generates only the points without the background
> containing the faults. I need the background to select which earthquakes
> coalesce on which fault. Is there an alternative?
> 
> eq.pts<-list("sp.points",eq, col="blue", lwd=0.5, pch = 4)
>    
> spplot(faults,"Dip", xlim = c(110000,120000),
>         ylim = c(3760000,3890000),
>         sp.layout=list(eq.pts),
>         col = heat.colors(3))
> 
> select.spatial(eq)
> 
> Cheers,
> 
> Julius Tesoro
> 
> 


Unfortunately, it looks like select.spatial() wipes the plotting region by
executing it's own call to plot(). However, the function it's self is very,
very simple, just type:

select.spatial

To see what goes on inside. It looks like you could obtain point-wise
selection by just calling identify():

identify( coordinates( eq )[,1], coordinates( eq )[,2]

To use areas, call locator() and then process the results using
point.in.polygon().

As for whether this will work using a spplot-- I really couldn't say. I was
not able to reproduce a spplot using the information you provided-- lack of
a working example may be a reason you got nothing but silence on R-sig-geo.

Good luck!

-Charlie

-----
Charlie Sharpsteen
Undergraduate
Environmental Resources Engineering
Humboldt State University
-- 
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