spplot - polygons with colored borderlines

Hi Roger,

thank you for your reply. After sending my email to R-sig-Geo I recognized
that you answered a similar question somedays ago.

However, if I use col = "transparent" some of my polygons are only "colored
dots in the space".

Is there no posibility to get filled colored polygons and colored borders?
I believe that grid.polygon() as used in spplot() fills to the exact 
polygon boundary, so adding coloured boundary lines might only add a pixel 
in some places on some devices, half a point line width on vector devices. 
So if the polygons are only "dots", then that is simply their size. In 
spplot() I do not think that extracting and passing a colour vector is 
easy. It could be done with base graphics, but the plot order of the 
contiguous polygons would determine which got the extra pixels, and which 
got overpainted. I think that col="transparent" is about as much as you 
can get, really.

Roger
Thank you,
Ingo

On Tue, 26 May 2009, Ingo Holz wrote:

Hi,

I am using function spplot (library sp) to plot polygons:

spplot(SPDF, "var", col.regions=topo.colors(100))

SPDF is a SpatialPolygonsDataFrame

Some of my polygons are very small and you can not see the color of the
polygon (only the black borderlines).

I could use

spplot(as(SPDF, "SpatialLinesDataFrame"), "variable1",
col.regions=topo.colors(100))

to get colored borderlines.

Is there a possibility to get filled colored polygons with borderlines
in the same color?
Although it isn't obvious, you use the col= argument passed through to
grid.polygon() used internally - see ?gpar after loading the gris package.
You'll find that col="transparent" is OK:

library(rgdal)
scot_BNG <- readOGR(system.file("vectors", package = "rgdal")[1],
  "scot_BNG")
spplot(scot_BNG, "SMR")
spplot(scot_BNG, "SMR", col="transparent")

Hope this helps,

Roger

Thank you for your help.
Best wishes,
Ingo

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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no

spplot - polygons with colored borderlines

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