ANN算法总结

• kd-tree

  kd-tree works poorly in high dimensions (k<30) 自己实验的时候差不多20到30左右吧，超过之后，就真的很慢了

　　kd-tree搜索的时间复杂度

 　　其中k是feature的维度

• faiss

  support high-dimensional vectors of 50 to 1000+ dimensions use gpu

   

• annoy

  Works better if you don't have too many dimensions (like <100) but seems to perform surprisingly well even up to 1,000 dimensions