Hi:

A couple of things:

(1) It's coord_equal(), not coord-equal() in ggplot2.
(2) For those who want to use Google Maps, I'll just mention that there is
an RgoogleMaps package with a nice vignette on CRAN.

HTH,
Dennis

On Tue, Aug 24, 2010 at 3:17 PM, Pierre Roudier <pierre.roudier@gmail.com>wrote:

> Hello Thiago,
>
> First, I owe you and the list a reproducible example (my first example
> does not run properly - my bad):
>
> dat <- data.frame(x=runif(50), y=runif(50),
> category=sample(letters[1:3], size=50, replace=TRUE),
> continuous=runif(50))
> # You may want to do some spatial analysis on that data.frame
> library(sp)
> coordinates(dat) <- ~x+y
> # Some spatial analysis here
>
> # Now you want to plot it
> library(ggplot2)
> df <- as.data.frame(dat) # backtransforms dat into a data.frame object
> (ggplot2 does not handle sp objects)
> # Here I chose to plot the continuous variable with the size of the
> bubbles, and the categorical variable with the colours
> my.plot <- ggplot(data=df, aes(x=x, y=y)) +
> geom_point(aes(size=continuous, colour=category)) + coord-equal()
> print(my.plot)
>
> Second, about plotting a shape file: yes, it is possible. Consider
> this blog entry for example:
>
> http://blog.revolutionanalytics.com/2009/11/choropleth-challenge-result.html
>
> Basically, you want to use either geom_path() for simple state
> boundaries, or geom_polygon() for polygons (e.g. you want to map some
> attribute by state).
>
> Sorry I haven't much experience with this. That could be a good
> question on the ggplot2 mailing list
> (http://groups.google.com/group/ggplot2).
>
> Pierre
>
>
> 2010/8/25 Thiago Veloso <thi_veloso@yahoo.com.br>:
> >   Hello, Matthew.
> >   Just a superb complement of yours.
> >   I was about to ask the same question to Pierre and Paul, after thanking
> them for the useful and functional tip. I managed to follow the ggplot
> examples, but a next step would involve plotting my interest points over a
> shape file (state contour).
> >   Is that possible?
> >   Best wishes,
> >   Thiago.
> >
> > --- On Tue, 24/8/10, Matthew Landis <landis@isciences.com> wrote:
> >
> > From: Matthew Landis <landis@isciences.com>
> > Subject: Re: [R-sig-Geo] Mapping multiple attributes at once
> > To: r-sig-geo@stat.math.ethz.ch
> > Date: Tuesday, 24 August, 2010, 11:47
> >
> >  I've been following this topic with some interest, since this is
> something I might like to do fairly often.  I'm not that familiar with
> ggplot2, but it looks really useful.  Is there a way to overplot (or
> underplot) a shapefile (e.g. of coastlines) with the approach suggested by
> Paul?
> >
> > Matt
> >
> > On 8/24/2010 10:25 AM, Paul Hiemstra wrote:
> >> In addition to the reply by Pierre Roudier, take a look at the ggplot2
> >> pacakge. An example:
> >>
> >
> >
> > -- ~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Matthew Landis, Ph.D.
> > Research Scientist
> > ISciences, LLC
> > 61 Main St. Suite 200
> > Burlington VT 05401
> > 802.864.2999
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
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> >
> >
> >
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