Got scipy's KD-tree to handle inserts and deletes without rebuilding. Three things I learned [P]

I built a small library called whitetree for exact Mahalanobis nearest-neighbour search on low-dimensional sensor data that keeps arriving. The idea is old. Whiten with the Cholesky factor of the covariance so Mahalanobis becomes Euclidean, then keep several scipy cKDTrees instead of one so inserts