[Openspace] GeoDa centroids

[Julia Koschinsky]

German,

The "Add Centroids" function in GeoDa adds central points (the average of the x-y vertices that define your polygon). You don't need to add these to create weights matrices. 

There are two types of weights matrices you can create in GeoDa: 

1) distance-based (distance bands and k-nearest neighbor)
For the distance-based weights, GeoDa automatically computes the central point of your polygon even if you haven't added them to your table.

2) contiguity-based (queen and rook, with different contiguity orders). For the contoguity-based weights, you don't need central points since these weights are based on shared borders (rook) and/or borders and corners (queen).

Julia

---- Original message ----
>Date: Fri, 02 Nov 2007 12:25:07 -0600
>From: "German Muchnik Izon" <german at unm.edu>  
>Subject: [Openspace] GeoDa centroids  
>To: openspace at sal.uiuc.edu
>
>Hi,
>
>I have a shapefile that does not come with x-y 
>coordinates. If I select "add centroids" using GeoDa I get 
>some type of x and y coordinate for each observation. 
>Would this be valid for creating weight matrices?
>
>Thank you for the help,
>German.
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