[R-sig-Geo] Question:manipulating spatial data using combination of Maptools and Splancs

[Roger Bivand]

On Tue, 20 Sep 2005, kostas karis wrote:

> Roger hi,
> First of all, i finally made the code ran thanks to your advices.Thank u 
> very much.U are right that i need the coastline only for display and 
> specifically, i need only the mainland as my main objective is to find, if 
> there is, a correlation between seismicity and rainfall (hydrologically 
> induced earthquakes).The thing is that the coastline of Greece is very 
> fragmented, not solid as France or Spain for example.So , by default i have 
> to use a polygon with more than one ring. Do you suggest that this is a task 
> that cannot be done with R?

Well, it is not feasible to use multiple rings in splancs. The spatstat 
package lets you use multiple rings, but I'm far from sure how many rings 
is a sensible number. If your research question is as you describe it, you 
can subset to take one ring, or a small number of rings with the largest 
areas and numbers of events. But in any case, you may be needing to look 
for association between seismicity and rainfall in time and space, that 
extreme precipitation events precede seismicity? I think that sorting that 
out first might give some more handles, and importing polygons is then not 
such an important problem. If the polygon shapefile only needs to be an 
outline for visualisation, you can also use readShapeLines() in maptools.

Roger

> I have read the latest R news and i have checked the sslib.I think it 'll be 
> of some use along the way. Thanks again for the tip!
> 
> K.
> 
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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