I just updated my oldish Local Density Analysis script to Python (v.lda.py) and created a new companion script (v.nn.py) for measuring the Nearest Neighbor coefficient for a vector points file, or the Nearest Neighbor between two files as a measure of correspondence (or lack thereof) between the two maps.
The LDA script will calculate the local density coefficient for a group of points, as an index of clustering, and between two different vector maps as a measure
of the amount of similarity between points on two different maps.
Both scripts are available in the GASS_ADDONS site.
Michael
____________________
C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University
voice: 480-965-6262 (SHESC), 480-727-9746 (CSDC)
fax: 480-965-7671 (SHESC), 480-727-0709 (CSDC)
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu
On Jul 1, 2011, at 9:00 AM, <grass-user-request@lists.osgeo.org> <grass-user-request@lists.osgeo.org> wrote:
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1. Re: v.generalize issues (Markus Metz)
----------------------------------------------------------------------
Message: 1
Date: Thu, 30 Jun 2011 17:04:52 +0200
From: Markus Metz <markus.metz.giswork@googlemail.com>
Subject: Re: [GRASS-user] v.generalize issues
To: Christian Guirreri <christian@guirreri.com>
Cc: grass-user@lists.osgeo.org
Message-ID: <BANLkTikq6fY1nT6NYK7HR3iq=jAoxHJzXQ@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1On Thu, Jun 30, 2011 at 4:47 PM, Christian Guirreri
<christian@guirreri.com> wrote:I'm on GRASS 6.4.1. QGIS 1.7.0
In this version, v.generalize is still broken. You would need a recent
version of GRASS 6.4.2. For Windows, you can get a recent version
here:http://wingrass.fsv.cvut.cz/grass64/
Markus M
On Thu, Jun 30, 2011 at 10:18 AM, Markus Metz
<markus.metz.giswork@googlemail.com> wrote:On Thu, Jun 30, 2011 at 4:01 PM, Christian Guirreri
<christian@guirreri.com> wrote:I'm a brand new user to GIS?- my goal right now is to heavily simplify
Tiger
2010 county and distrct data, without producing gaps between boundaries.
I've been testing this with v.generalize in grass via QuantumGIS - I've
had
tons of issues with the Grass toolbox crashing, but have narrowed down
to
using the Hermite algorithm. While it works, I'm having some bizarre
issues
with it. Apologies for the cross-post with the PostGIS mailing list.In the attached gif of California counties, from left to right, I have
used
the following tolerance values with the Hermite algorithm:
?- original
?- 1.0
?- 0.08
?- 0.01
?- 0.00001Why do counties disappear entirely as I decrease the tolerance?
This problem has been fixed in GRASS 6.4 only 2 weeks ago (June 13).
Please update your GRASS version if possible.Markus M
In the Grass Tools I choose the v.generalize function. I choose Boundary
as
the feature type (though I've tried checking others, as well as all of
them
and it doesn't seem to change anything). Everything else is default,
except
for tolerance as notated above.When I tested this originally on only Arkansas and Mississippi, I got
really
nice results. I then tried it on the entire US and had the missing
counties
problem. So I tried only California, and still have the same issue.I've tried other algorithms, but this has so far given me the detail I
want
- of course sans counties! Any thoughts?Thanks,
?- Chris
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