[R-sig-eco] [R-sig-Geo] Need an algorithm to identify spatial clusters

[Miguel Eduardo Gil Biraud]

Hi,

I'm not an expert at all but maybe this page will put you in the right
direction.
http://home.dei.polimi.it/matteucc/Clustering/tutorial_html/

>From what I understood you might be interested in looking into K-means
clustering, which a quick google search of R K-means returns a few
results and among them:
http://www.r-cookbook.com/node/23

Cheers,
Miguel

On Tue, Apr 14, 2009 at 18:26, Mark Andersen <manderse at nmsu.edu> wrote:
> Hello, all,
>
> I am currently interested in simulating the initiation and spread of forest
> fires in simulated landscapes consisting of 2 tree species (a native and an
> invasive). I'm simulating fire seasons of fixed length; fires can start at
> any time and in either tree species during this fire season, and spread
> through the simulated forest according to a simple percolation-like process.
> I have developed the algorithms for this in Matlab, and don't anticipate any
> problems converting them to R if I need to.
>
> However, it's the next task that has me at a loss. At the end of each fire
> season, there will be several burned patches on the simulated landscape; the
> number of these patches won't necessarily correspond to the total number of
> fires that season, because fires may coalesce. I need to count how many of
> these burned patches there are, and find the size of each. It seems that
> there should be an algorithm available to do this, but I haven't found one,
> possibly because I haven't been using the right search criteria. I used
> RSiteSearch("spatial cluster"), and got many references to the spatclus
> package. However, from the spatclus documentation it appears that this is
> not quite what I'm looking for. Spatclus looks like it picks out potential
> clusters of occurrence of some phenomenon (such as earthqukes or cancer); I
> need something that will delineate clusters of contiguous pixels with the
> same value (i.e., burned in my simulations). Could anyone point me towards
> such an algorithm, or help me get started finding one?
>
> --
> Dr. Mark C. Andersen, Professor
> Department of Fish, Wildlife, and Conservation Ecology
> New Mexico State University
> Las Cruces, NM 88003
> 575-646-8034
> fax: 575-646-1281
> web: web.nmsu.edu/~manderse
>
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