abdiv (version 0.2.0)

strong: Strong's dominance index

Description

Strong's dominance index measures the maximum departure between the observed proportions and a perfectly even community.

Usage

strong(x)

Arguments

x

A numeric vector of species counts.

Value

Strong's dominance index, \(0 \leq D_W < 1\). The index is undefined if x sums to 0, and we return NaN in this case.

Details

Strong's dominance index is defined as $$D_W = \max_i \left [ \frac{b_i}{N} - \frac{i}{S} \right ],$$ where \(b_i\) is the abundance of the \(i\)th species, ordered from smallest to largest, \(N\) is the total number of counts, and \(S\) is the number of species observed.

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

References

Strong WL. Assessing species abundance uneveness within and between plant communities. Community Ecology. 2002;3:237-246.

Examples

# NOT RUN {
x <- c(9, 0, 1, 2, 5, 2, 1, 1, 0, 7, 2, 1, 0, 1, 1)
strong(x)
# }