Pianka's niche-overlap index

Computes Pianka's symmetric index of overlap between two non-negative activity profiles \(p\) and \(q\): $$\frac{\sum_i p_i q_i}{\sqrt{\left(\sum_i p_i^2\right)\left(\sum_i q_i^2\right)}}.$$

Usage

pianka_index(p, q)

Arguments

p

Numeric vector of non-negative values (counts or relative frequencies) for the first biological identity data 1 (e.g. activity, population size, etc) across ordered time bins.

q

Numeric vector of non-negative values (same length as p) for the second biological identity (e.g. activity, population size, etc) across ordered time bins.

Value

A single numeric value in [0, 1]; larger values indicate greater overlap.

Details

Pianka's index does not require inputs to sum to 1, but both vectors must be non-negative and not all zero.

Examples

set.seed(1)
n <- 10
p <- rpois(n, 3); q <- rpois(n, 3)
pianka_index(p, q)
#> [1] 0.828351