margalef {abdiv}

Margalef's richness index

Description

Margalef's richness index

Usage

margalef(x)

Arguments

x

A numeric vector of species counts.

Details

For a vector x of species counts, Margalef's index is

D = \frac{S -1}{\log N},

where S is the total number of species observed and N is the total number of counts.

This index is appropriate only for raw counts, not transformed counts or proportions.

Equivalent to margalef() in skbio.diversity.alpha.

Value

The value of Margalef's index, D \geq 0. This index is undefined when the total number of counts is 1 or 0, in which case we return NaN.

References

Margalef R. Information theory in ecology. General Systems 3. 1958;36-71.

Examples

x <- c(15, 6, 4, 0, 3, 0)
margalef(x)