questions about food web metrics
Dear Jarrett, most of the indices you're looking for are available in the package sna (social network analysis). If your data are not one-mode networks but rather bipartite, then you could look at the function as.one.mode in package bipartite to convert two-mode into sna-compatible one-mode networks. HTH, Carsten
Jarrett Byrnes wrote:
Dear R-sig-eco group, I'm working on a food web analysis project in R, and rather than re- invent the wheel, I was wondering if any of you had suggestions for packages, or had written code yourselves for calculations of some of the more involved algorithmic metrics, such as Number of Food Chains Average (and variance in) Food Chain Length Shortest Path Length between two species Longest Path Length between two species (all of which I guess feeds back to the ave. food chain length...) Finding Loops (chains in which a taxa occurs twice) Trophic Similarity between species Clustering Coefficients and any other food web metrics of interest. Also, any methods for dealing with network stability and the analysis of weighted networks not already in the sna or network package - particularly those dealing with food webs - would be great. In addition to my own work, I'd like to compile all of these methods into a foodweb package to post on CRAN for general usage, so, any contributions would be most welcome! -Jarrett ---------------------------------------- Jarrett Byrnes Postdoctoral Associate, Santa Barbara Coastal LTER Marine Science Institute University of California Santa Barbara Santa Barbara, CA 93106-6150 http://www.lifesci.ucsb.edu/eemb/labs/cardinale/people/byrnes/index.html [[alternative HTML version deleted]]
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Dr. Carsten F. Dormann Department of Computational Landscape Ecology Helmholtz Centre for Environmental Research UFZ Permoserstr. 15 04318 Leipzig Germany Tel: ++49(0)341 2351946 Fax: ++49(0)341 2351939 Email: carsten.dormann at ufz.de internet: http://www.ufz.de/index.php?de=4205