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新的等价类划分算法-计数法
引用本文:农修德,徐章艳,阮慎,杨炳儒. 新的等价类划分算法-计数法[J]. 计算机工程与应用, 2009, 45(2): 48-50. DOI: 10.3778/j.issn.1002-8331.2009.02.013
作者姓名:农修德  徐章艳  阮慎  杨炳儒
作者单位:广西师范大,学计算机系,广西,桂林,541004;广西南宁师范高等专科学校,数计系,广西,崇左,532200;广西师范大,学计算机系,广西,桂林,541004;北京科技大学,信息工程学院,北京,100083;广西师范大,学计算机系,广西,桂林,541004;北京科技大学,信息工程学院,北京,100083
基金项目:广西教育科研立项项目 
摘    要:目前,基于基数排序的等价类划分算法有较低的时间复杂度但存在以下不足:属性值跳跃性大时会产生大量空队列;排序后仍需O(|PU|)的时间才实现划分,求出等价类,排序没能发挥应有作用。为此,设计了一种新算法,通过属性值映射避免大量空队列产生,通过增加一个记录等价类长度信息的计数数组,排序后仅需O(|U|)就可实现划分,求出等价类。整个算法时间复杂度为O(|CU|),空间复杂度为O(|U|),为求等价类划分提供了一个新的解决办法。

关 键 词:粗糙集  等价类  划分  计数法
收稿时间:2008-07-22
修稿时间:2008-10-13 

Counting method-novel algorithm for computing partition
NONG Xiu-de,XU Zhang-yan,RUAN Shen,YANG Bing-ru. Counting method-novel algorithm for computing partition[J]. Computer Engineering and Applications, 2009, 45(2): 48-50. DOI: 10.3778/j.issn.1002-8331.2009.02.013
Authors:NONG Xiu-de  XU Zhang-yan  RUAN Shen  YANG Bing-ru
Affiliation:1.Department of Computer,Guangxi Normal University,Guilin,Guangxi 541004,China 2.Department of Mathematics and Computer Science,Guangxi Nanning Normal College,Chongzuo,Guangxi 532200,China 3.College of Information Engineering,Science and Technology University of Beijing,Beijing 100083,China
Abstract:At present,the algorithm for computing partition based on radix sorting has lower time complexity than the others,but it also has the following shortcomings:it will create a lot of idle storage when there is a big increment between two attribution value;for computing the partition,its time complexity is as high as O(|PU|) after sorting.For improving the efficiency of computing partition,a novel algorithm for computing partition is designed.It does not create a lot of idle storage by mapping the attribution values to sequential natural number.And it records the length of equivalence classes to compute the partition by defining a count array.Its time complexity is as only low as O(|U|).The time complexity of the new algorithm is O(|CU|),the space complexity is O(|U|).It offers a new method for computing the partition of the universe U.
Keywords:rough set  equivalence class  partition  counting method  
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