How do you calculate Gini - simpsons index?

The Gini-Simpson index, also known as the Gini index or Simpson's diversity index, quantifies diversity within a dataset. To calculate it, first determine the proportion of each category (or species) in the dataset. Then, use the formula (D = 1 - \sum (p_i^2)), where (p_i) is the proportion of each category. The resulting value ranges from 0 to 1, indicating the level of diversity; a higher value signifies greater diversity.