On Sat, 9 Aug 2008, adjemian wrote:
List,
I'm having some trouble importing a Geoda generated distance
band weight matrix into R for use with the spdep regression
tools. The "read.gwt2nb" function does not work, and even
when I try to import a manually created version of the
matrix, I cannot seem to get it into the right format to
avoid frame errors when attempting to estimate lag/error
models.
In general, it is sensible to include the verbatim command and error
messages from your console. The output of sessionInfo() is also helpful,
as it shows what platform you are using, and what the versions of loaded
packages are.
My guess is that you need to pay attention to the arguments to
read.gwt2nb(). Have you tried the example provided on the help page? Note
that the function only reads the neighbour links into an nb object, and
you have to retrieve the distances as shown in the example. It may help to
copy preceding commands in your question too, so that the origin og the
values given to the arguments is made plain. str() of those objects may
also help, if not too bulky.
I think that the errors in the model fitting functions will go away when
the weights are read in correctly. Once they are imported, it may be
interesting to re-create them with dnearneigh() and nbdist() within R,
just for safety's sake.
Hope this helps,
Roger
Once I import the data in properly, I intend to
perform a test of the common factor hypothesis, which is
unavailable in Geoda.
Up to this point, I've tried to use "mat2listw", but the
program returns a faulty "matrix not standardized" warning,
and then produces the frame errors after regression
commands. So, I have two questions:
1) Is there a pre-packaged "read.gwt2..." function that
imports distance based weight matrices into R for use with
spdep?
2) Failing that, how can I import a distance band weight
matrix into R (for use with spdep) while avoiding frame
errors?
Thanks in advance for your help!
-Mike Adjemian
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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: [EMAIL PROTECTED]
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