[R-sig-Geo] turning polygons shapefile into quadrats

[Roger Bivand]

On Tue, 30 Dec 2008, francesco wrote:

> Dear List,
>
> I have been banging my head on a problem for three days now, so I 
> believe the time has come to look for help.
>
> I have a polygon shapefile with an irregular grid and I would like to 
> turn the polygons in the shapefile into tiles to use with "quadratcount" 
> method in spatstat package.
>
> I have been coercing back and forth with lists, slots, classes and I got 
> a little lost into trying to turn the coordinates of the shapes into 
> tiles.
>
> The final objective is to extract statistics on points falling inside 
> each polygons.  The points are a SpatialPointsDataframe class with 
> attributes which will be analysed in each polygon as if the polygons 
> were containers.
>
> I hope I have explained clearly and that someone can point towards a 
> method to use for this.

Not really clear without a simple code example. If you need to find out 
which points are inside which polygon, use an overlay() method. It isn't 
clear what quadratcount might have to do with this, so you'll need to 
explain that. You can also use overlay() methods to find out which grid 
cells points belong to.

Hope this helps,

Roger


>
> PS  I am relatively new to R, but it's fantastic.
>
> Cheers,
> --------------------------------------
> Francesco Pirotti
> Dept. Te.S.A.F./CIRGEO
> University of Padua
> Viale dell'Università 16
> I-35020 Legnaro (PD)
> tel.       +39 049 827 2710
> fax.      +39 049 827 2686
> mob.    +39 349 55 39 261
> @mail   francesco.pirotti at unipd.it
> skypeID francesco197576
> http://www.cirgeo.unipd.it/cirgeo/francescopirotti.htm
>
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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