# [R] Monmonier algorithm

Thibaut Jombart jombart at biomserv.univ-lyon1.fr
Mon Aug 27 13:39:15 CEST 2007

```Hello,

almost one year ago on this list:

> On Wed, 29 Mar 2006, Thibaut Jombart wrote:

>> Hello list,
/>> /
/>> does anyone know if Monmonier algorithm is available in R? I've
checked /
/>> several spatial libraries, but I didn't find anything related to it. /
/>> However, there is a huge documentation and I may have missed it. /
/>> /
/>> Before coding it, I'd like to be sure it doesn't already exist. /

> Googling, I found:

> http://www-med-physik.vu-wien.ac.at/staff/rub/abstracts/ISCB_2005.pdf

> which is a poster, and refers to using R for boundary finding, and
other software for data management and display.  >Perhaps the authors
are able to help by making code available, the poster looks like a nice
example of spatial data >analysis.

> --
> Roger Bivand
> Economic Geography Section, Department of Economics, Norwegian School of
> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
> e-mail: Roger.Bivand at nhh.no

Basically, Monmonier algorithm aims at finding maximum-difference
boundaries between geo-referenced objects. It requires a set of
georeferenced objects along with matrix of distances among these objects.

Monmonier algorithm is now implemented in the adegenet package
'monmonier' and 'optimize.monmonier'. Despite the package is devoted to
genetic data analysis, these functions can handle other kind of data as
well.

The main difference I can see between this implementation and the
original algorithm is that here, the function uses objects connected on
a neighbouring graph rather than polygons of a Voronoi tesselation.
Thus, Delaunay triangulation shall be used to recover the original
version of the algorithm, but other graphs are also possible (e.g.
Gabriel's graph).

Regards,

Thibaut.

--
######################################
Thibaut JOMBART
CNRS UMR 5558 - Laboratoire de Biométrie et Biologie Evolutive
Universite Lyon 1
43 bd du 11 novembre 1918
69622 Villeurbanne Cedex
Tél. : 04.72.43.29.35
Fax : 04.72.43.13.88
jombart at biomserv.univ-lyon1.fr
http://lbbe.univ-lyon1.fr/-Jombart-Thibault-.html?lang=en

```