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实现动态聚类全局最优的一种算法

AN ALGORITHM TO GLOBAL OPTIMIZATION IN NON-HIERARCHICAL CLUSTER ANALYSIS

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【作者】 顾世梁

【Author】 Gu Shiliang(Dept.of Agron.,Jiangsu Agric.Coll.,Yangzhou 225009)

【机构】 江苏农学院农学系

【摘要】 聚类分析是把n个个体分成k个内在相近类群的一种多元统计分析方法。非系统(又称动态)聚类一般能得到比系统聚类更为合理的结果,但稳定性差的问题非常突出。以目标函数为最小迹[Mintr(W)]为条件的动态聚类全局最优解的算法分以下三步。第一步:对个体依次易组试分,若这种试分能优化目标函数,则固化试分。进行一至多轮的试分改组,直至任一个体的改组均不能改善目标函数时为止,记录下目标函数值及相应的分类结果。第二步:设定一临界正值C_i,当试分改组增大目标函数,但又不超过C_i时仍实施改组,该轮试分过程一般会使目标函数劣化,但应对可能出现的目标函数最小化植和相应的聚类结果作出记录。对所有个体试分后,改变(降低)C_i值:C_(i+1)=αC_i(0<α<1)。以上两步交互运算多次。第三步:类群的重组过程,合并组中心欧氏距离最近的两类,并把平方乘积和阵迹tr(W_i)量大的类群一分为二以保持总组数k不变。重复以上过程多次,在一定轮次(10~12)内目标函数未有改善时结束寻优过程。经多组模拟和实用数据运算,该算法对一般聚类分析问题都能达到全局最优解。

【Abstract】 CIuster analysis is to partition n objects into k non-empty coherent clusters,There are wide ranges ofapplications in genetics and other areas.Non-hlerarchical clustering usually produces local instead of global optimal re-sults in most cluster analyses.The poor robustness is the main problem of existing methods.A new algorithm wasproposed in this paper to reach the global optimization.The algorithm begins with obtaining a trial transfer of an ob-ject between initial(or intermediate) groups.The first step is to transfer those objects from one group into another,ifsuch transferring decreases the tr(W) value(or other criterla),i.e.,Δ<(0(Δ=Qnew-Qold),until no further transfer-ring can be made.The better solution ls recorded at the end. In the second step,worsening state is forced tO accept,provided that it is under proper criterion Ci,i.e.,0≤Δ≤Ci,This step usually reverses the objective function,but thepossible minimal solutions should be recorded in the process,The above two steps are repeated alternat ively withchanging criterion:Ci+1=αCi.The third step is a group reforming process,which provides dramatic change of inter-mediate groups;The abeve three steps are repeated until there is no progress in 10~12 rounds.The algorithm is reli-able to get the global optimum in most cases.

【基金】 江苏省教委资金资助
  • 【分类号】S11
  • 【被引频次】18
  • 【下载频次】129
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