Simpson Diversity Index — simpson • taxdiv

Calculates the Simpson diversity index (1 - D) for a community.

Usage

simpson(community, type = c("gini_simpson", "inverse", "dominance"))

Arguments

community: A numeric vector of species abundances.
type: One of "inverse" (1/D), "gini_simpson" (1 - D), or "dominance" (D). Default is "gini_simpson".

Value

A numeric value representing the Simpson index.

Details

Simpson's dominance index D is calculated as: $$D = \sum_{i=1}^{S} p_i^2$$ The Gini-Simpson index is \(1 - D\) and the inverse Simpson is \(1/D\).

See also

shannon() for Shannon diversity.

Examples

comm <- c(10, 5, 8, 3, 12)
simpson(comm)
#> [1] 0.7631579
simpson(comm, type = "inverse")
#> [1] 4.222222