custom header test
pianka_var(m = matrix(rpois(80, 1), nrow = 10))
Takes a niche utilization matrix as in put and returns the variance of Pianka's niche overlap index.
A large value for variance implies that some species pairs show high niche overlap and others show low niche overlap. A low value for variance implies that niche overlap (high or low) is very similar among all species pairs.
The resource utilization matrix (rows = species, columns = discrete resource categories) may include zeroes, but no negative numbers or missing values. Relative resource within a species is first calculated, so the rows need not sum to 1.0.
Winemiller, K.O. and E.R. Pianka. 1990. Organization in natural assemblages of desert lizards and tropical fishes. Ecological Monographs 60: 27-55.
obsVar <- pianka_var(m=matrix(rpois(40,0.5),nrow=8))
pianka niche overlap index.