labdsv (version 2.0-1)

isamic: Indicator Species Analysis Minimizing Intermediate Occurrences

Description

Calculates the degree to which species are either always present or always absent within clusters or types.

Usage

isamic(comm,clustering,sort=FALSE)

Value

A data.frame of species indicator values

Arguments

comm

a matrix or data.frame of samples, species as columns, samples as rows

clustering

a vector of numeric cluster memberships for samples, or a classification object returned from pam, partana, or slice

sort

if TRUE, return in order of highest value to lowest rather than input order

Author

David W. Roberts http://ecology.msu.montana.edu/droberts/droberts.html

Details

Calculates the constancy (fractional occurrence of each species in every type), and then calculates twice the the sum of the absolute values of the constancy - 0.5, normalized to the number of clusters (columns).

References

Aho, K., D.W. Roberts, and T.W. Weaver. 2008. Using geometric and non-geometric internal evaluators to compare eight vegetation classification methods. J. Veg. Sci. 19(4):549-562.

See Also

indval

Examples

data(bryceveg)
data(brycesite)
clust <- cut(brycesite$elev,5,labels=FALSE)
isamic(bryceveg,clust)