lazy learner
деревья для поиска ближайших значений (KD, Q, R, Ball)

- k-dimensional tree 
Recursively splits data along coordinate axes.
at each node pick a dimension, split at median, each node becomes a hyperrectangle in d-dimensional space. 

- Quad-Tree
Each node is a square region. If too many points fall into a region subdivide into 4 equal quadrants

- rectangle tree
Each node stores several children, each with a Minimum Bounding Rectangle covering many points or objects. Subtrees group spatially close objects. Insertions try to minimize rectangle enlargement.

- Ball-Tree
Each node contains:
 - a center point
 - a radius enclosing all points in that node
Two children represent two balls that split the data