[GRASS-user] New tools for spatial analysis

[Michael Barton]

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 at lists.osgeo.org> <grass-user-request at lists.osgeo.org> wrote:

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> Today's Topics:
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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 at googlemail.com>
> Subject: Re: [GRASS-user] v.generalize issues
> To: Christian Guirreri <christian at guirreri.com>
> Cc: grass-user at lists.osgeo.org
> Message-ID: <BANLkTikq6fY1nT6NYK7HR3iq=jAoxHJzXQ at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> 
> On Thu, Jun 30, 2011 at 4:47 PM, Christian Guirreri
> <christian at 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 at googlemail.com> wrote:
>>> 
>>> On Thu, Jun 30, 2011 at 4:01 PM, Christian Guirreri
>>> <christian at 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
>>>> ?- 0.00001
>>>> 
>>>> Why 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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>>>> 
>> 
>> 
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> End of grass-user Digest, Vol 63, Issue 3
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