[Biomod-commits] Environmental and biotic data at different locations

[Wilfried Thuiller]

Dear Charles,
Do not too much the interpolations techniques. In which format are your data? Are they originally ArcGIS raster or grid data? 
If yes, better practice to use the raster package with the extract function. 
Else, I guess your approach is probably the best one.
Best
Wilfried


Le 7 déc. 2010 à 21:22, Charles Novaes de Santana a écrit :

> Dear all,
> 
> First of all, I would like to say "Congratulations" to all the
> developers of BIOMOD. It is a GREAT tool and I can not imagine the
> hard work you need to mantain it working so nice! Thank your for
> everything!
> 
> I am just starting to use Biomod, and I have a question that maybe is
> a tipical "newbie" question :)
> 
> My biotic data (presence of species) are not at the same grid that my
> environmental data (temperature and precipitation). And my
> environmental data are at a regular grid while my biotic data are at
> points irregularly spaced.
> 
> I think the best thing to do in this case is to make an interpolation
> of my environmental data to find the values of temperature and
> precipitation at the same grid points of my biotic data. To do it, I
> am using the function "interp" from the package "akima". Am I correct?
> Is ther another option?
> 
> Here, just an example similar of my case: environmental data at a
> regular gridpoint. Biotic data at points irregularly spaced.
> 
> environmental$lat <- c(2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5,
> 7.0, 7.5, 8.0)
> environmental$lon <- c(-38.5, -38.0, -37.5, -37.0, -36.5, -36.0,
> -35.5, -35.0, -34.5, -34.0,-33.5, -33.0, -32.5, -32.0, -31.5, -31.0)
> biotic$lat <- c(4.222, 4.250, 4.34, 4.7, 4.71, 4.77, 4.811, 4.99)
> biotic$lon<- c(-35.1, -34.8, -34.7, -34.4, -34.38, -34.21, -33.23, -32.77)
> 
> biotic$temp <- interp (environmental$lon, environmental$lat,
> environmental$temp, biotic$lon, biotic$lat)
> 
> Thank you in advance for any help!
> 
> best regards,
> 
> Charles
> 
> -- 
> Um axé! :)
> 
> --
> Charles Novaes de Santana
> PhD student - Global Change
> Laboratorio Internacional de Cambio Global
> Department of Global Change Research
> Instituto Mediterráneo de Estudios Avanzados(CSIC/UIB)
> Calle Miquel Marques 21, 07006
> Esporles - Islas Baleares - España
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--------------------------
Dr. Wilfried Thuiller
Laboratoire d'Ecologie Alpine, UMR CNRS 5553
Université Joseph Fourier
BP53, 38041 Grenoble cedex 9, France
tel: +33 (0)4 76 51 44 97
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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