[R-sig-Geo] Spplot: Specifying individual point symbols

[Oscar Perpiñan]

Use groups instead:

spplot(meuse["elev"], groups=ifelse(meuse$dist < 0.3, 1, 2), pch=c(1, 16))

Oscar.
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Oscar Perpiñán Lamigueiro
Dpto. Ingeniería Eléctrica (ETSIDI-UPM)
Grupo de Sistemas Fotovoltaicos (IES-UPM)
URL: http://oscarperpinan.github.io
Twitter: @oscarperpinan


2014-03-07 15:29 GMT+01:00 Mark Payne <markpayneatwork at gmail.com>:
> Hi,
>
> I have a problem where I would like to have both the colour and the symbol
> varying in an spplot plot. Unfortunately, specifying a list of pch values
> doesn't seem to work. See the following example
>
> library(sp)
> data(meuse)
> coordinates(meuse) <- ~x +y
> #Lets plot the elevation
> spplot(meuse,"elev")
> #And now the distance
> spplot(meuse,"dist")
> #Lets plot the points close to the river with open points
> spplot(meuse,"elev",
>        colorkey=TRUE,
>        pch=ifelse(meuse$dist<0.3,1,16))
>
> What I'm aiming for is to have all the points close to the river open
> circles (pch=1), and all the points further from the river to be closed
> (pch=16). However, the pch symbols don't seem to be propigating through
> into the panel function correctly. The problem seems to arise somewhere the
> Fill.call.groups() function, but I can't quite figure out where....
>
> This type of trick is legitimate in lattice, which is where my inspiration
> came from eg:
>
> x <- rnorm(1000)
> y <- rnorm(1000)
> z <- sqrt(x^2 + y^2)
> xyplot(y~x,pch=ifelse(z<1,16,1),asp="iso",cex=1)
>
> As you can see, I have managed to change the symbol according  to the
> distance from the centre.
>
> Am I asking too much of spplot to try and achieve this type of thing - we
> are starting to getting pretty complex here! Or am I doing something wrong?
>
> Best wishes,
>
> Mark
>
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>
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