Sort order in GeoDa weight files (.gwt)
Raffaele Vacca
Dear all,
I am replicating a GeoDa .gwt file (distance based weight file) in R
using the "spdep" library.
I know the structure of .gwt files (first line then 3 columns: "from",
"to", "distance"), and the task is quite easy, but I have one question:
are the regions in the second column of the .gwt file sorted in a
specific order?
(I'm talking about .gwt files created by Open GeoDa using a specific
field of the original shapefile as region ID)
In the first column of the .gwt file (the "from" column) regions are
sorted in the same order as in the original shapefile. However, in the
second column (the "to" column), within each "from" region, "to" regions
don't follow the same order of the first column, nor are they sorted in
region IDs increasing/decreasing order.
Maybe the second column order is random?
By the way, I need to replicate a .gwt file to use it again in Open
GeoDa, because in Open GeoDa under Windows 7 when trying to create a
distance based weight file (Tools > Weights > Create) I can't change the
distance band in the menu window: the value is stuck to the default (the
minimum value allowing each region to have at least one neighbour). This
is a problem that I didn't have in the "original" GeoDa under Windows XP.
Thank you for any help.
---
Raffaele Vacca
PhD candidate Urban and Local European Studies
Department of Sociology and Social Research
Room 208, II Floor
Universitￜ degli Studi di Milano-Bicocca
Via Bicocca degli Arcimboldi, 8
20126, Milano
r.v...@campus.unimib.it
Julia Koschinsky
Sorry for the delay. Please note that we added the ability to manually change the distance band in the latest version of OpenGeoDa.
Re. the order of the 2nd column in .gwt files: since we do not use the order of the 2nd column in OpenGeoDa, it's undefined, i.e. neither sorted nor random (the order could change on different machines).
Best,
Julia
Università degli Studi di Milano-Bicocca
Via Bicocca degli Arcimboldi, 8
20126, Milano
r.v...@campus.unimib.it
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Julia Koschinsky, Ph.D.
Research Director
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Arizona State University
School of Geographical Sciences and Urban Planning
GeoDa Center for Geospatial Analysis and Computation
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Raffaele Vacca
sorry for *my* delay, but I don't know why I didn't get your message in my mail client, and I ran into it on
the web only today.
Thank you for you clarification.
By the way, my original problem in OpenGeoDa (under Windows 7) was exactly this: even if in principle, as
you said, the program gave the ability to manually change the distance band for a gwt file, in practice in
the gwt creation window that value was stuck to the default, I mean the program didn't accept my manual
edits on that value. I hope that was a problem only with my machine.
Best,
Raffaele
Il 05/10/11 21.19, Julia Koschinsky ha scritto:
>> Universit� degli Studi di Milano-Bicocca
>> Via Bicocca degli Arcimboldi, 8
>> 20126, Milano
>> r.v...@campus.unimib.it
>>
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* Raffaele Vacca *
PhD candidate Urban and Local European Studies
Department of Sociology and Social Research
Universit� degli Studi di Milano-Bicocca
Room 208, II Floor