[R-sig-Geo] plotting polygons of one shapefile in different colors?
Roger.Bivand at nhh.no
Thu Sep 26 20:57:52 CEST 2013
On Thu, 26 Sep 2013, cyndy-jer wrote:
> Hi Maren -
> (yes I'm Cyndy :)
> Well, thanks, but yikes! Surely there is an easier way? I've gotten pretty
> close by trying to use spplot and rColorBrewer, but I'm not quite there. I
> have 3 'n' values as part of my SpatialPolygonDataFrame, and somehow the
> below only plots 2 of them,
The easier way is to get to know and like factors, categorical variables
typically with few levels:
coordinates(meuse.grid) <- c("x", "y")
gridded(meuse.grid) <- TRUE
but if the plotted variable is numeric (or integer):
meuse.grid$ffreq1 <- as.integer(meuse.grid$ffreq)
you get trouble because at= by default splits the range of the variable
into 20, cycling the colours. You can fix at=
spplot(meuse.grid, "ffreq1", at=seq(0.5, 3.5, 1),
but if your variable is really categorical, convert it to factor
representation, and live gets easier.
> (my dataframe is named 'gimmie')
> # the below yields a plot of three colors
> display.brewer.pal(numpoly, "Accent")
> #the below yields my map but with only two of the three above colors, yet
> the scale bar shows
> #three colors with the three values I KNOW are in my 'n' values in the
> spplot(gimmie, c("n"), xlim=c(minx,maxx), ylim=c(miny,maxy),
> col.regions=brewer.pal(numpoly, "Accent"))
> ? I don't see why this doesn't work as I expect. Any ideas, anyone?
> View this message in context: http://r-sig-geo.2731867.n2.nabble.com/plotting-polygons-of-one-shapefile-in-different-colors-tp7584720p7584727.html
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