On Sun, Aug 16, 2009 at 12:20 PM, Rebecca
Ross<[email protected]> wrote:
>
> Dear All,
>
> I am new to this list, so apologies if this question has been asked and
> answered many times before!
>
> I would like to overlay a bubble chart onto a map so that the bubbles
> correspond to particular points on the map. I have the shape file for the map
> and the lat long co-ordinates for the points. Could anyone tell me how to put
> the two together? The suggestions I found so far are plot.Map and
> plot.Spatial,
> neither of which work.
>
> I am working to a bit of a deadline, so a response today would be really
> helpful.
To read foo.shp:
install.packages("rgdal")
require(rgdal)
map = readOGR("/path/to/maps/","foo")
plot(map)
then you can do:
points(p$x,p$y)
or whatever to overlay on it. If a 'bubble chart' is just points
scaled by some factor, you can either use the 'symbols' function in R
or use pch and cex options to plot - with something like:
p = data.frame(x=1:10,y=1:10,size=1:10)
plot(p$x,p$y,pch=19,cex=p$size)
hope that helps!
Barry
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