[R-sig-Geo] spplot with legend only, and legend inside the plotting area

[Jon Olav Skoien]

Hi Mauricio,

Maybe not the most elegant solution, but one possibility is to extract 
the colors and text of the legend from the spplot-object and plot it 
with legend():
p1 = spplot(xyz, cex=10, alpha=0.7)
str(p1)
# This has auto.key = "bottom" by default.
cols = p1$legend$bottom$args$key$points$col
txt = p1$legend$bottom$args$key$text[[1]]
plot.new()
legend(0.3,0.7, legend = txt, fill = cols, border = cols, bty = "n")

legend() has lots of parameters that can help you adjusting the plot if 
you need to modify the layout.

Cheers,
Jon

On 06-Mar-12 18:23, Mauricio Zambrano-Bigiarini wrote:
> Hi all,
>
>
> I need to produce two different spplot figures of spatial points, and 
> I would like to ask your help for the creation of the second one:
>
> 1) the first figure has to show the values but without any legend:
>
> library(sp)
> xyz = data.frame(expand.grid(x=1:10,y=1:10),rnorm(100))
> coordinates(xyz)=~x+y
> spplot(xyz, cex=10, alpha=0.7, auto.key=FALSE)
>
> (I don't have any problem with this)
>
>
> 2) The second figure has to show ONLY the legend for the values of the 
> previous figure (without plotting the points), inside the plotting area.
>
> I tried with:
>
> spplot(xyz, cex=0, alpha=0.7, auto.key=TRUE, key.space="center")
>
> but it doesn't work.
>
>
> I know that "center" is not a valid argument for 'key.space', but I 
> don't figure out how to produce this second figure.
>
>
> I would really appreciate any help with this.
>
> Thanks in advance,
>
> Mauricio Zambrano-Bigiarni
>


-- 
Jon Olav Skøien
Joint Research Centre - European Commission
Institute for Environment and Sustainability (IES)
Land Resource Management Unit

Via Fermi 2749, TP 440,  I-21027 Ispra (VA), ITALY

jon.skoien at jrc.ec.europa.eu
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