[Biomod-commits] Building up data matrix

Wilfried Thuiller wilfried.thuiller at ujf-grenoble.fr
Mon Aug 31 15:04:33 CEST 2009

Dear Matt,

There are various methods in R to extract the environmental data from 
grids to selected points (like the function "sample" in ArcGIS)

One option is to use the fantastic library maintained by Rob Hijmans 
"raster" under the R forge website.
You upload the grids, then stack them and then extract the values of a 
RasterLayer or RasterStack for a set of xy coordinates (your presence 
and/or absences). This is done via the function xyValues()

Note that we are also in the process of transforming BIOMOD to be able 
to project the potential distributions of species directly onto grids 
(using the predict function of the package raster actually).

Hope it helps,

Matt Hill a écrit :
> Hi, 
> I'm pretty new to the modelling scene, am in the process of investigating
> various modelling methods for an invasive species in Australia.
> I've been using Maxent with the BIOCLIM variables to project distributions
> into future climate scenarios.
> I was wondering if there is a guide or instructions on the most simple way
> to construct a data matrix for use in BIOMOD with it's range of methods?
> Ideally I would want to use the same BIOCLIM variables, but I am happy to
> start off with baseline CRU data. I understand the principle of the matrix,
> just not sure on how to create them.
> Any help would be much appreciated,
> Matt.
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> Biomod-commits at lists.r-forge.r-project.org
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Wilfried Thuiller
Laboratoire d'Ecologie Alpine, UMR-CNRS 5553
Université J. Fourier
BP 53, 38041 Grenoble Cedex 9, France
Tel: +33 (0)4 76 63 54 53
Fax: +33 (0)4 76 51 42 79

Email: wilfried.thuiller at ujf-grenoble.fr
Home page: http://www.will.chez-alice.fr
Website: http://www-leca.ujf-grenoble.fr/equipes/tde.htm

FP6 European MACIS project: http://www.macis-project.net
FP6 European EcoChange project: http://www.ecochange-project.eu

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