count sketch（basic count sketch .count min sketch算法)

basic count sketch &count sketch&count min sketch 中文讲解：

https://blog.csdn.net/dm_ustc/article/details/45972811

basic count sketch的频数估计值fa的期望=count sketch 的频数估计值fa的期望

basic count sketch的频数估计值fa的方差=count sketch 的频数估计值fa的方差

count sketch只是将basic count sketch 重复t次取平均 （提高准确率）

basic count sketch

https://stackoverflow.com/questions/6811351/explaining-the-count-sketch-algorithm

 

 

 count min sketch

 

  

 

 

 

 

 

 

 

 更多的hash function有助于减少collision 从而使得count min sketch的结果和真实频数差距越小