Computes Jaccard distances between the columns of a 0-1-matrix.
Usage
jaccard(regmat)
Arguments
regmat
0-1-matrix. Columns are species, rows are regions.
Value
A symmetrical matrix of Jaccard distances.
Details
The Jaccard distance between two species is 1-(number of regions where
both species are present)/(number of regions where at least one
species is present). As a similarity coefficient, this is S22 in
Shi (1993).
Thank you to Laurent Buffat for improving this function!
References
Shi, G. R. (1993) Multivariate data analysis in palaeoecology and
palaeobiogeography - a review. Palaeogeography,
Palaeoclimatology, Palaeoecology 105, 199-234.