k-means

choose K :
 by hand, by human input, human insight.
ask what's your purpose of running kmeans.

can use Elbow method, but it doesn't always work.

初始化中心点init_k_centers()：

1， random

2， kmeans++

3， max-min

701-svm-recitation

701 rec5-kernel

real word text classification system - nlp