compute_simpson_index: Compute the Local Inverse Simpson Index (LISI)
In scPOP: Metrics for Benchmarking scRNA-Seq Batch Correction

Compute the Local Inverse Simpson Index (LISI)

compute_simpson_index(
  D,
  knn_idx,
  batch_labels,
  n_batches,
  perplexity = 15,
  tol = 1e-05
)

`D`	Distance matrix of K nearest neighbors.
`knn_idx`	Adjacency matrix of K nearest neighbors.
`batch_labels`	A categorical variable.
`n_batches`	The number of categories in the categorical variable.
`perplexity`	The effective number of neighbors around each cell.
`tol`	Stop when the score converges to this tolerance.