基于模拟退火的动态聚类算法

提出了一个基于模拟退火的动态聚类算法，用模拟退火的全局优化能力来解决常规动态聚类方法中聚类结果对初始中心的敏感性问题，仿真结果表明，它是一个具有全局最优解的动态聚类方法。     

基于自适应阈值的自动提取关键帧的聚类算法

利用无监督聚类算法来提取关键帧是一种常用的方法，但该算法对类别数和初始类划分较敏感，在对视频内容一无所知的情况下，要求预先指定聚类数目是一个很困难的问题．提出一种二次聚类的方法；第1次以镜头内相邻两帧的相似度为数据样本进行聚类（分成两类），计算确定第2次聚类所需的阈值；第2次采用动态聚类的ISODATA算法，以视频序列的帧为数据样本进行聚类，得到最终聚类结果．最后在每类中自动提取距其类中心最近的帧为关键帧．该算法简单且行之有效，无需预定义任何阈值（如聚类数目）．对大量不同特点的视频进行了实验，该算法均取得了较好的实验结果．     

一种新的基于遗传算法的动态聚类算法

为了在聚类数不明确的情况下实现聚类分析,提出一种新的结合最近邻聚类和遗传算法的动态聚类算法.新算法包括两个阶段:第一阶段用最近邻聚类算法根据最近邻方法把最相似的实例分到同一个簇中并根据一些相似性或相异性度量过滤掉噪声数据从而得到初始聚类集,第二阶段是遗传优化阶段,利用动态聚类评估函数,动态地合并初始聚类集,从而获得接近最优的解.最后对算法进行了实验仿真,实验结果表明方法在事先不知道聚类数的情况下能够有效地进行聚类.     

TGFCM:基于模糊聚类的中文文本挖掘的新方法

提出一种新的动态模糊聚类的方法，针对传统的模糊聚类需要预先确定聚类数的问题，提出采用动态自组织映射神经网络来确定聚类数，并通过文本向量空间模型和TF-IDF方法来确定文本的特征向量，再将动态自组织映射神经网络得到的聚类数，用模糊C均值算法（FCM）函数处理，得到聚类的结果。该算法同仅用动态自组织映射神经网络算法的运行结果相比，具有运行聚类结果精度高的优点，模糊聚类更适合处理语义的多样性和文本归属的模糊性，实验验证了算法的有效性。     

K-means聚类算法的研究综述

K-均值聚类算法（K-means）是基于划分的聚类算法中的典型算法,针对K-means算法初始聚类中心存在对K依赖的缺陷,提出一种新的选取K-means算法初始聚类中心的方法,该方法提高聚类结果的有效性和稳定性;还提出一种极值选择法,将最大距离法和最小距离法相结合,进一步提高初始聚类中心选择的准确性。     

新的K-均值算法最佳聚类数确定方法

K-均值聚类算法是以确定的类数k和随机选定的初始聚类中心为前提对数据集进行聚类的。通常聚类数k事先无法确定,随机选定的初始聚类中心容易使聚类结果不稳定。提出了一种新的确定K-均值聚类算法的最佳聚类数方法,通过设定AP算法的参数,将AP算法产生的聚类数作为聚类数搜索范围的上界kmax,并通过选择合适的有效性指标Silhouette指标,以及基于最大最小距离算法思想设定初始聚类中心,分析聚类效果,确定最佳聚类数。仿真实验和分析验证了以上算法方案的可行性。     

面向对象的竞争合作学习遥感影像聚类算法

目前的遥感图像聚类方法通常存在一些不可避免的缺陷,如类别数难于自动确定、聚类速度缓慢、聚类过程不稳定以及聚类结果存在椒盐噪声等。结合竞争合作学习和面向对象的图像处理技术的优点,提出一种无需事先指定确切类别数的面向对象的竞争合作学习图像聚类算法。为了加快聚类速度并获得稳定的聚类结果,还提出一种基于动态包围空间的中位切分算法,用于选定初始聚类中心。通过对遥感影像的聚类实验,验证了该算法能够自动获得聚类数并得到满意的聚类结果,说明算法具有很好的实用价值。     

一种改进的K—means聚类算法

K—means算法是最常用的一种基于划分的聚类算法,但该算法需要事先指定K值、随机选择初始聚类中心等的缺陷,从而影响了K—means聚类结果的稳定性。针对K—means算法中的初始聚类中心是随机选择这一缺点进行改进,利用提出的新算法确定初始聚类中心,然后进行聚类,得出最终的聚类结果。实验证明,该改进算法比随机选择初始聚类中心的算法性能得到了提高,并且具有更高的准确性及稳定性。     

基于划分和层次的混合动态聚类算法*

针对划分聚类对初始值较为敏感以及层次聚类时间复杂度高等缺陷,提出了一种基于划分和层次的混合动态聚类算法HDC-PH。该算法首先使用划分聚类快速生成一定数量的子簇,然后以整体相似度的聚类质量评价标准来动态改变聚类数目,同时给出了聚类过程中孤立点的剔除方法。实验结果表明,HDC-PH算法的性能明显优于划分和层次算法,提高了聚类质量,并获得了更自然的聚类结果。     

K 均值聚类算法在银行客户细分中的研究

研究银行客户细分问题,对客户进行分类,应针对获利最大的为识别目标.为了减少主观性分析,采用 K 均值聚类算法是数据挖掘技术在银行客户细分中一种重要方法,K 均值算法存在对初始值敏感且容易陷入局部最优值的缺点,导致银户客户分类准确率低.为了提高银行客户细分的准确率,提出了一种基于改进的 K 均值聚类的银行客户细分方法.算法首先通过有效指数法动态调整初始聚类数 K,减轻了聚类结果对初始聚类数 K 的依赖,通过自适应最佳密度半径来确定聚类中心,降低聚类中心对分类结果的影响,加快聚类速度,最后通过初始聚类数 K 和聚类中心对银行客户进行细分.在 C++ 语言平台上,采用某市银业的客户分类数据对算法进行实验,结果表明,算法有效地克服了传统 K 均值算法易陷入局部最优值,提高了客户分类准确率,聚类结果更加合理,为银行决策者提高有效的参考,并带来更多的收益.     

基于密度与划分方法的聚类算法设计与实现

在分析常用聚类算法的特点和适应性基础上提出一种基于密度与划分方法的聚类算法。该算法根据数据对象密度分布状态来自动确定聚类簇密度吸引中心点和聚类簇的初始划分;然后利用划分的方法,根据密度可达定义来寻找密度可达数据对象簇,从而完成数据对象簇的最终聚类。实验证明该算法能够很好地处理具有任意形状和大小的簇,能够有效地屏蔽噪声和离群点的影响和发现孤立点;同时也减小了输入参数对领域知识的依赖性。     

Combining multiple clusterings using evidence accumulation

We explore the idea of evidence accumulation (EAC) for combining the results of multiple clusterings. First, a clustering ensemble - a set of object partitions, is produced. Given a data set (n objects or patterns in d dimensions), different ways of producing data partitions are: 1) applying different clustering algorithms and 2) applying the same clustering algorithm with different values of parameters or initializations. Further, combinations of different data representations (feature spaces) and clustering algorithms can also provide a multitude of significantly different data partitionings. We propose a simple framework for extracting a consistent clustering, given the various partitions in a clustering ensemble. According to the EAC concept, each partition is viewed as an independent evidence of data organization, individual data partitions being combined, based on a voting mechanism, to generate a new n /spl times/ n similarity matrix between the n patterns. The final data partition of the n patterns is obtained by applying a hierarchical agglomerative clustering algorithm on this matrix. We have developed a theoretical framework for the analysis of the proposed clustering combination strategy and its evaluation, based on the concept of mutual information between data partitions. Stability of the results is evaluated using bootstrapping techniques. A detailed discussion of an evidence accumulation-based clustering algorithm, using a split and merge strategy based on the k-means clustering algorithm, is presented. Experimental results of the proposed method on several synthetic and real data sets are compared with other combination strategies, and with individual clustering results produced by well-known clustering algorithms.     

基于网格密度和局部敏感哈希函数的并行化聚类算法

针对大数据背景下基于划分的聚类算法中存在初始中心敏感,节点间通信开销大以及集群效率低下等问题,提出了基于网格密度和局部敏感哈希函数的PBGDLSH-MR并行化聚类算法。首先,对初始数据集提出网格密度策略(GDS)获取初始中心点,有效避免了随机选取引起的初始中心敏感的问题;其次,提出基于局部敏感哈希函数的数据分区(DP-LSH)用于投射关联性较大的数据对象到同一子数据集中,得到map上的数据分区,并设计相似性度量公式(SI)对数据分区结果进行评价,从而降低了节点间的通信开销;接着设计自适应分组策略(AGS)处理数据分区中数据倾斜的问题,进而有效地提高了集群效率;最后,结合MapReduce计算模型并行挖掘簇中心,生成最终聚类结果。实验结果表明,PBGDLSH-MR算法的聚类效果更佳,同时在大数据环境下能有效地提高并行计算的效率。     

基于Spark并行的密度峰值聚类算法

针对FSDP聚类算法在计算数据对象的局部密度与最小距离时,由于需要遍历整个数据集而导致算法的整体时间复杂度较高的问题,提出了一种基于Spark的并行FSDP聚类算法SFSDP。首先,通过空间网格划分将待聚类数据集划分成多个数据量相对均衡的数据分区;然后,利用改进的FSDP聚类算法并行地对各个分区内的数据执行聚类分析;最后,通过将分区间的局部簇集合并,生成全局簇集。实验结果表明,SFSDP与FSDP算法相比能够有效地进行大规模数据集的聚类分析,并且算法在准确性和扩展性方面都有很好的表现。     

A hybrid approach for data clustering based on modified cohort intelligence and K-means

Clustering is an important and popular technique in data mining. It partitions a set of objects in such a manner that objects in the same clusters are more similar to each another than objects in the different cluster according to certain predefined criteria. K-means is simple yet an efficient method used in data clustering. However, K-means has a tendency to converge to local optima and depends on initial value of cluster centers. In the past, many heuristic algorithms have been introduced to overcome this local optima problem. Nevertheless, these algorithms too suffer several short-comings. In this paper, we present an efficient hybrid evolutionary data clustering algorithm referred to as K-MCI, whereby, we combine K-means with modified cohort intelligence. Our proposed algorithm is tested on several standard data sets from UCI Machine Learning Repository and its performance is compared with other well-known algorithms such as K-means, K-means++, cohort intelligence (CI), modified cohort intelligence (MCI), genetic algorithm (GA), simulated annealing (SA), tabu search (TS), ant colony optimization (ACO), honey bee mating optimization (HBMO) and particle swarm optimization (PSO). The simulation results are very promising in the terms of quality of solution and convergence speed of algorithm.     

稳定的K-多均值聚类算法

指定K个聚类的多均值聚类算法在K-均值算法的基础上设置了多个次类,以改善K-均值算法在非凸数据集上的劣势,并将多均值聚类问题形式化为优化问题,可以得到更优的聚类效果。但是该算法对初始原型敏感,且随机选取原型的方式使聚类结果不稳定。针对上述问题,提出一种稳定的K-多均值聚类算法,并对该算法的复杂度与收敛性进行了简要讨论。该算法先基于数据样本的最邻近关系构造图,根据图的连通分支将数据分为若干组,取每组数据的均值点作为初始原型,再用交替迭代的方法对优化问题进行求解,得到最后的聚类结果。在人工数据集和真实数据集上的实验表明,该算法具有更稳定更优越的聚类效果。     

Cluster center initialization algorithm for K-modes clustering

Partitional clustering of categorical data is normally performed by using K-modes clustering algorithm, which works well for large datasets. Even though the design and implementation of K-modes algorithm is simple and efficient, it has the pitfall of randomly choosing the initial cluster centers for invoking every new execution that may lead to non-repeatable clustering results. This paper addresses the randomized center initialization problem of K-modes algorithm by proposing a cluster center initialization algorithm. The proposed algorithm performs multiple clustering of the data based on attribute values in different attributes and yields deterministic modes that are to be used as initial cluster centers. In the paper, we propose a new method for selecting the most relevant attributes, namely Prominent attributes, compare it with another existing method to find Significant attributes for unsupervised learning, and perform multiple clustering of data to find initial cluster centers. The proposed algorithm ensures fixed initial cluster centers and thus repeatable clustering results. The worst-case time complexity of the proposed algorithm is log-linear to the number of data objects. We evaluate the proposed algorithm on several categorical datasets and compared it against random initialization and two other initialization methods, and show that the proposed method performs better in terms of accuracy and time complexity. The initial cluster centers computed by the proposed approach are close to the actual cluster centers of the different data we tested, which leads to faster convergence of K-modes clustering algorithm in conjunction to better clustering results.     

Clustering spatial data with a geographic constraint: exploring local search

Spatial data objects that possess attributes in the optimization domain and the geographic domain are now widely available. For example, sensor data are one kind of spatial data objects. The location of a sensor is an attribute in the geographic domain, while its reading is an attribute in the optimization domain. Previous studies discuss dual clustering problems that attempt to partition spatial data objects into several groups, such that objects in the same group have similar values in their optimization attributes and form a compact region in the geographic domain. However, previous studies do not clearly define compact regions. Therefore, this paper formulates a connective dual clustering problem with an explicit connected constraint given. Objects with a geographic distance smaller than or equal to the connected constraint are connected. The goal of the connective dual clustering problem is to derive clusters that contain objects with similar values in the optimization domain and are connected in the geographic domain. This study further proposes an algorithm CLS (Clustering with Local Search) to efficiently derive clusters. This algorithm consists of two phases: the ConGraph (standing for Connective Graph) transformation phase and the clustering phase. In the ConGraph transformation phase, CLS first transforms the data objects into a ConGraph that captures geographic constraints among data objects and selects initial seeds for clustering. Then, the initial seeds selected nearby data objects and formed coarse clusters by exploring local search in the clustering phase. Moreover, coarse clusters are merged and finely turned. Experiments show that CLS algorithm is more efficient and scalable than existing methods.     

一种改进的混合属性数据聚类算法

K-prototypes算法是处理混合属性数据的主要聚类算法,但是存在对初值敏感、参数依赖和易受噪声干扰等问题。为了克服以上缺点,该文对K-prototypes算法的初始中心点选择进行了研究与分析,提出了一种基于近邻法的初始中心点选择策略对算法进行改进,算法先利用近邻法获得初始中心点集和k值,然后进行K-prototypes运算,最后加入识别异常数据点的规则。改进后的算法成功解决了传统K-prototypes算法的缺陷,而且具有更好的分类精度和稳定性。经实验证明,改进算法是正确和有效的,明显优于传统的K-prototypes算法。     

Extensions to the k-Means Algorithm for Clustering Large Data Sets with Categorical Values

The k-means algorithm is well known for its efficiency in clustering large data sets. However, working only on numeric values prohibits it from being used to cluster real world data containing categorical values. In this paper we present two algorithms which extend the k-means algorithm to categorical domains and domains with mixed numeric and categorical values. The k-modes algorithm uses a simple matching dissimilarity measure to deal with categorical objects, replaces the means of clusters with modes, and uses a frequency-based method to update modes in the clustering process to minimise the clustering cost function. With these extensions the k-modes algorithm enables the clustering of categorical data in a fashion similar to k-means. The k-prototypes algorithm, through the definition of a combined dissimilarity measure, further integrates the k-means and k-modes algorithms to allow for clustering objects described by mixed numeric and categorical attributes. We use the well known soybean disease and credit approval data sets to demonstrate the clustering performance of the two algorithms. Our experiments on two real world data sets with half a million objects each show that the two algorithms are efficient when clustering large data sets, which is critical to data mining applications.