# skbio.diversity.alpha.simpson¶

skbio.diversity.alpha.simpson(counts)[source]

Calculate Simpson’s index.

State: Experimental as of 0.4.0.

Simpson’s index is defined as 1 - dominance:

$1 - \sum{p_i^2}$

where $$p_i$$ is the proportion of the community represented by OTU $$i$$.

Parameters

counts (1-D array_like, int) – Vector of counts.

Returns

Simpson’s index.

Return type

double

Notes

The implementation here is 1 - dominance as described in 1. Other references (such as 2) define Simpson’s index as 1 / dominance.

References

1

http://folk.uio.no/ohammer/past/diversity.html

2

http://www.pisces-conservation.com/sdrhelp/index.html