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GWR with GWT file

3 messages · Jay Douillard, Danlin Yu, Roger Bivand

Original
Jay Douillard
# 
I'm working on a project where the distance between two polygons may be a poor measure of connectivity(contigious polygons that may have an impassible mountain chain between them. To get a better measure of distance I've used road network distances from population weighted centroids of the polygons. I've created a row standarized gwt style file using arcgis's network tools, and a bit of table editing. I can successfully import this into R.
File format in "old style GWT"
for example: 
473
1 2 .111
1 3 .22
1 4 .66
2 1 .11


Is possible to use your own weighting scheme in spgwr? Is it using a listw object? I couldn't find any indication in the documentation.

thanks!
   

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Jay Douillard
Geospatial Technical Lead
604.827.4401
Human Early Learning Partnership 
www.earlylearning.ubc.ca
Danlin Yu
# 
Jay:

Some time ago, the alternative weighting scheme issue was raised, but no 
solution as far as I know was present. As for now, I don't think SPGWR 
is taking other weighting schemes than the coordinates determined 
distance. I believe it is doable, however, by implementing some sort of 
alternative distance and replace the *coord* argument in the gwr function.

Hope this helps.

Cheers,
Danlin Yu

Jay Douillard ??:

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Roger Bivand
    

    

      
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On Thu, 11 Mar 2010, Jay Douillard wrote:

        

            

      
      
      
    

        
Jay,

It isn't, but it probably wouldn't be too hard to do under certain 
conditions. The non-neighbours would be treated as outside the bandwidth, 
I suppose, otherwise one is looking at a full matrix for asymmetric road 
networks. The source for spgwr is on the r-spatial project on sourceforge, 
so you could check out what there is and see how one might add a listw= 
argument to gwr() for a given bandwidth first - branching around the 
spDistsN1() in .GWR_int() after passing the listw object through.

Roger