Hi Suzanne,
It sounds like you are dealing with an Inhomogeneous Poisson Point
Process (the simplest). The intensity function lambda(mu) of this
process is the density of points near mu. i.e. the process is poisson
locally, and the intensity varies over the region according to some
underlying function or surface (such as soil chemistry)
e.g.
> plot(rpoispp(function(x,y){300*cos(2*pi*x)},300)) # taken from
Adrian Baddeley's notes
The first step would then be interpolate your soil characteristics into
global functions (either through delaunay triangulation, smoothing
method (loess), or krigging). This allows you to estimate soil
characteristics where your trees are, and derive vectors of the same
length (although with some error).
There may also be away of involving the idea of a global funciton into
the actual inference process, but I haven't thought about that deeply
and my memory cells aren't stirred to recall a suitable reference.
Hope this was of some use.
Rohan Sadler
Suzanne E. Blatt wrote:
Hello all, I'm attempting to conduct spatial analysis of trees within a plot. I want to see if the trees are spatially correlated to soil characteristics, say pH, or moisture content. I think one way to do it is with mpl, however, my soil characteristics were not taken at exactly the same locations as my trees and further, the vectors aren't the same length. I'm getting the impression, largely from the error messages, that length matters, ie. they must be the same. In my case this is impossible. The example listed in the file:///tmp/Rtmp1608/.R/library/spatstat/html/mpl.html regarding 'soilsurvey' using 'soilchem' as the covariate does not seem to be located in library(spatstat) nor library(splancs). I'm trying to see how that example works, but can't locate it. Can anyone tell me how to circumvent the 'length' problem or direct me to the location of 'soilsurvey' and 'soilchem' so I can see how those datasets are set up. Thanks,Suzanne
__________________________________________________________________Try AOL and get 1045 hours FREE for 45 days!http://free.aol.com/tryaolfree/index.adp?375380 ______________________________________________ R-help at stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
PhD Student, Ecosystems Research Group (ERGO) School of Plant Biology (Botany), Faculty of Natural & Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia Ph: +61 8 9380 7914 Fax: +61 8 9380 7925 email: rsadler at agric.uwa.edu.au ERGO's web site:<http://www.botany.uwa.edu.au/ergo>