sw_diversity_index.sw_diversity_index
sw_diversity_index.sw_diversity_index(arr)Calculate the Shannon Wiener diversity index (H’) for a community.
The Shannon Wiener index quantifies species diversity by accounting for both species richness and evenness. It is defined as:
H' = -SUM(p_i * ln(p_i))where p_i is the proportion of individuals belonging to species i.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| arr | array - like | A one-dimensional array of non-negative values representing species counts. | required |
Returns
| Name | Type | Description |
|---|---|---|
| float | The Shannon Wiener diversity index. Returns 0.0 if only one species is present or if the input is empty. |
Notes
- Zero counts are ignored in the calculation.
- The natural log (ln) is used.
- Higher values indicate greater diversity.
Examples
>>> sw_diversity_index([50, 30, 20])
1.0297>>> sw_diversity_index([1])
0.0