[R-sig-Geo] shapefiles plotting and colouring

[Hisaji Ono]

Hi.

I've tried to draw choropleth maps by rmap package as follows.

library(rmap)

mySF <- shapefile("columbus.shp")

 crime <- mySF$CRIME

# user-defined legend
 classes <- c(50,100,500,1000,5000)
 breaks <- length(classes) + 1
 classNo <- crime < classes[1]
 for(i in 1:(breaks - 1))
   classNo <- classNo + (crime >= classes[i] & crime < classes[i + 1]) * i

 classNo <- classNo + (crime >= max(classes)) * breaks
 plot(mySF, f=gray(1 - classNo/breaks)) # draw map
 lines(mySF, col="red") # draw outlines

----- Original Message ----- 
From: "Paolo Cavallini" <cavallini at faunalia.it>
To: <r-sig-geo at stat.math.ethz.ch>
Sent: Friday, October 31, 2003 11:57 PM
Subject: [R-sig-Geo] shapefiles plotting and colouring


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> Hi all.
> it may be a silly question, but: how can I, after reading a shapefile with
the
> appropriate library, draw them with different colours (or grey shades)
> according to different database fields (read through RODBC)? The idea is
> similar to the polygon command, but using shp as polygons and database
fields
> as qualifiers.
> Thanks for any suggestions.
> Ciao.
> paolo