skbio.diversity.alpha.inv_simpson

skbio.diversity.alpha.inv_simpson(counts, finite=False)

Calculate inverse Simpson index.

The inverse Simpson index (\(1 / D\)), a.k.a., Simpson’s reciprocal index, is defined as:

\[1 / D = \frac{1}{\sum_{i=1}^S{p_i^2}}\]

where \(S\) is the number of taxa and \(p_i\) is the proportion of the sample represented by taxon \(i\).

Parameters:

counts1-D array_like, int

Vector of counts.

finitebool, optional

If True, correct for finite sampling when calculating \(D\).

Returns:

float

Inverse Simpson index.

See also

dominance

Notes

\(1 / D\) is a measurement of the effective number of species (ENS). It is equivalent to Hill number with order 2 (\(^2D\)).

Inverse Simpson index was originally described in [1].

References

[1]

Simpson, E. H. (1949). Measurement of diversity. Nature, 163(4148), 688-688.