[R] overlaying a levelplot on a map plot

[Felix Andrews]

You are plotting the entire lattice plot (including axes, margins etc)
in the grid viewport. What you want to do is to call the panel
function, panel.levelplot(), instead.

However, why not just

mm <- map('worldHires', plot = FALSE)
levelplot(z~x+y,xyz, mm = mm, panel = function(..., mm) {
    panel.levelplot(...)
    panel.lines(mm$x, mm$y)
})


On 23 April 2010 06:16, Simon Goodman <s.j.goodman at leeds.ac.uk> wrote:
> Thanks for those pointers.... making some progress now
>
> The following will put the levelplot on to the map, but the not with the
> co-ordinates aligned...
> The level plot appears on a slightly larger scale compared to the underlying
> map.
>
> In both the map and levelplot, the coordinates are in lon, lat decimal
> degrees.
> Hopefully I'm nearly there, with 1 or 2 tweaks.
>
>
> library(gridBase)
> mlat<-c(n1,n2)
> mlon<-c(n3,n4)
> map('worldHires', xlim = range(mlon), ylim = range(mlat))
> axis(1);axis(2);axis(3);axis(4)
>
> lvl.plot<-levelplot(z~x+y,xyz,pretty=TRUE,at=at,col.regions=cl)
> vps <- baseViewports()
> pushViewport(vps$inner, vps$figure, vps$plot)
> pushViewport(viewport(print(lvl.plot, newpage=FALSE)))
> popViewport()
> popViewport(3)
>
> However after the line 'pushViewport(viewport(print(lvl.plot,
> newpage=FALSE)))' an error is returned:
>
> Error in unit(x, default.units) :
>  (list) object cannot be coerced to type 'double'
>
>
>
>
>
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/overlaying-a-levelplot-on-a-map-plot-tp2019419p2021128.html
> Sent from the R help mailing list archive at Nabble.com.
>
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-- 
Felix Andrews / 安福立
Postdoctoral Fellow
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The Australian National University
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