虽然二次探测消除了主要集聚，要素   散列到同一位置将探测相同的备用电池。   这就是所谓的次级聚类。模拟结果表明，   它通常会导致低于每搜索一个额外的探头。

Although quadratic probing eliminates primary clustering, elements that hash to the same position will probe the same alternate cells. This is known as secondary clustering. Simulation results suggest that it generally causes less than an extra probe per search.

以上是文本片段从algorihms本书从马克·艾伦Wessis书。

Above is text snippet from algorihms book from Mark Allen Wessis book.

我的问题可以用例有一个人解释什么是次要clustring又是什么作者的仿真结果表明，它通常会导致低于每搜索一个额外的探针的意思。

My question can some one explain with example what is secondary clustring and what does author mean by "Simulation results suggest that it generally causes less than an extra probe per search".

谢谢！

推荐答案

二次聚类在你引述的一段文字的定义：而不是插入点附近，探测器将聚集各地的分

Secondary clustering is defined in the piece of text you quoted: instead of near the insertion point, probes will cluster around other points.

仿真结果表明，它通常会导致小于每搜索一个额外的探针是指某人试图插入或找到大量的数据在与二次探测哈希表，并发现，平均的，还需要不到两个探头查找哈希表中的正确位置。 （一个探针是当然需要插入或找哈希表中的任何的最小值。）

"Simulation results suggest that it generally causes less than an extra probe per search" means someone tried to insert or find lots of data in a hash table with quadratic probing, and found that, on average, less than two probes were needed to find the right spot in the hash table. (One probe is of course the minimum needed to insert or find anything in a hash table.)