On Wed, 2011-07-06 at 14:50 +0100, Sarah Leclaire wrote: > Hi, > > I would like to calculate the RELATIVE euclidean distance. Is there a > function in R which does it ? > > (I calculated the abundance of 94 chemical compounds in secretion of > several individuals, and I would like to have the chemical distance > between 2 individuals as expressed by the relative euclidean distance. > Some compounds are in very low abundance whereas others are in high > abundance, that's why I would like to correct for the abundance) > > Thanks, > Sarah
A simple solution to this is to transform the data and then compute the Euclidean distance using dist(). decostand(foo, method = "normalize") and disttransform(foo, method = "chord") in package BiodiversityR can do this for you without you having to write a function yourself. Pass the returned object to dist() to get the distances you want. HTH G -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
