k-ANMI: A mutual information based clustering algorithm for categorical data

Clustering categorical data is an integral part of data mining and has attracted much attention recently. In this paper, we present k-ANMI, a new efficient algorithm for clustering categorical data. The k-ANMI algorithm works in a way that is similar to the popular k-means algorithm, and the goodness of clustering in each step is evaluated using a mutual information based criterion (namely, average normalized mutual information – ANMI) borrowed from cluster ensemble. This algorithm is easy to implement, requiring multiple hash tables as the only major data structure. Experimental results on real datasets show that k-ANMI algorithm is competitive with those state-of-the-art categorical data clustering algorithms with respect to clustering accuracy.     

Partition-and-merge based fuzzy genetic clustering algorithm for categorical data

Categorical data clustering is a difficult and challenging task due to the special characteristic of categorical attributes: no natural order. Thus, this study aims to propose a two-stage method named partition-and-merge based fuzzy genetic clustering algorithm (PM-FGCA) for categorical data. The proposed PM-FGCA uses a fuzzy genetic clustering algorithm to partition the dataset into a maximum number of clusters in the first stage. Then, the merge stage is designed to select two clusters among the clusters that generated in the first stage based on its inter-cluster distances and merge two selected clusters to one cluster. This procedure is repeated until the number of clusters equals to the predetermined number of clusters. Thereafter, some particular instances in each cluster are considered to be re-assigned to other clusters based on the intra-cluster distances. The proposed PM-FGCA is implemented on ten categorical datasets from UCI machine learning repository. In order to evaluate the clustering performance, the proposed PM-FGCA is compared with some existing methods such as k-modes algorithm, fuzzy k-modes algorithm, genetic fuzzy k-modes algorithm, and non-dominated sorting genetic algorithm using fuzzy membership chromosomes. Adjusted Ranked Index (ARI), Normalized Mutual Information (NMI), and Davies–Bouldin (DB) index are selected as three clustering validation indices which are represented to both external index (i.e., ARI and NMI) and internal index (i.e., DB). Consequently, the experimental result shows that the proposed PM-FGCA outperforms the benchmark methods in terms of the tested indices.     

A fuzzy k-modes algorithm for clustering categorical data

This correspondence describes extensions to the fuzzy k-means algorithm for clustering categorical data. By using a simple matching dissimilarity measure for categorical objects and modes instead of means for clusters, a new approach is developed, which allows the use of the k-means paradigm to efficiently cluster large categorical data sets. A fuzzy k-modes algorithm is presented and the effectiveness of the algorithm is demonstrated with experimental results     

类属数据的贝叶斯聚类算法

针对类属型数据聚类中对象间距离函数定义的困难问题,提出一种基于贝叶斯概率估计的类属数据聚类算法。首先,提出一种属性加权的概率模型,在这个模型中每个类属属性被赋予一个反映其重要性的权重;其次,经过贝叶斯公式的变换,定义了基于最大似然估计的聚类优化目标函数,并提出了一种基于划分的聚类算法,该算法不再依赖于对象间的距离,而是根据对象与数据集划分间的加权似然进行聚类;第三,推导了计算属性权重的表达式,得出了类属型属性权重与其符号分布的信息熵成反比的结论。在实际数据和合成数据集上进行了实验,结果表明,与基于距离的现有聚类算法相比,所提算法提高了聚类精度,特别是在生物信息学数据上取得了5%~48%的提升幅度,并可以获得有实际意义的属性加权结果。     

A mutual information based face clustering algorithm for movie content analysis

This paper investigates facial image clustering, primarily for movie video content analysis with respect to actor appearance. Our aim is to use novel formulation of the mutual information as a facial image similarity criterion and, by using spectral graph analysis, to cluster a similarity matrix containing the mutual information of facial images. To this end, we use the HSV color space of a facial image (more precisely, only the hue and saturation channels) in order to calculate the mutual information similarity matrix of a set of facial images. We make full use of the similarity matrix symmetries, so as to lower the computational complexity of the new mutual information calculation. We assign each row of this matrix as feature vector describing a facial image for producing a global similarity criterion for face clustering. In order to test our proposed method, we conducted two sets of experiments that have produced clustering accuracy of more than 80%. We also compared our algorithm with other clustering approaches, such as the k-means and fuzzy c-means (FCM) algorithms. Finally, in order to provide a baseline comparison for our approach, we compared the proposed global similarity measure with another one recently reported in the literature.     

A k-populations algorithm for clustering categorical data

In this paper, the conventional k-modes-type algorithms for clustering categorical data are extended by representing the clusters of categorical data with k-populations instead of the hard-type centroids used in the conventional algorithms. Use of a population-based centroid representation makes it possible to preserve the uncertainty inherent in data sets as long as possible before actual decisions are made. The k-populations algorithm was found to give markedly better clustering results through various experiments.     

Non-dominated sorting genetic algorithm using fuzzy membership chromosome for categorical data clustering

In this research, a data clustering algorithm named as non-dominated sorting genetic algorithm-fuzzy membership chromosome (NSGA-FMC) based on K-modes method which combines fuzzy genetic algorithm and multi-objective optimization was proposed to improve the clustering quality on categorical data. The proposed method uses fuzzy membership value as chromosome. In addition, due to this innovative chromosome setting, a more efficient solution selection technique which selects a solution from non-dominated Pareto front based on the largest fuzzy membership is integrated in the proposed algorithm. The multiple objective functions: fuzzy compactness within a cluster (π) and separation among clusters (sep) are used to optimize the clustering quality. A series of experiments by using three UCI categorical datasets were conducted to compare the clustering results of the proposed NSGA-FMC with two existing methods: genetic algorithm fuzzy K-modes (GA-FKM) and multi-objective genetic algorithm-based fuzzy clustering of categorical attributes (MOGA (π, sep)). Adjusted Rand index (ARI), π, sep, and computation time were used as performance indexes for comparison. The experimental result showed that the proposed method can obtain better clustering quality in terms of ARI, π, and sep simultaneously with shorter computation time.     

Squeezer: An efficient algorithm for clustering categorical data

This paper presents a new efficient algorithm for clustering categorical data,Squeezer,which can produce high quality clustering results and at the same time deserve good scalability.The Squeezer algorithm reads each tuple t in sequence,either assigning t to an existing cluster (initially none),or creating t as a new cluster,which is determined by the similarities between t and clusters.Due to its characteristics,the proposed algorithm is extremely suitable for clustering data streams,where given a sequence of points,the objective is to maintain consistently good clustering of the sequence so far,using a small amount of memory and time.Outliers can also be handled efficiently and directly in Squeezer.Experimental results on real-life and synthetic datasets verify the superiority of Squeezer.     

A graph model for mutual information based clustering

We propose a graph model for mutual information based clustering problem. This problem was originally formulated as a constrained optimization problem with respect to the conditional probability distribution of clusters. Based on the stationary distribution induced from the problem setting, we propose a function which measures the relevance among data objects under the problem setting. This function is utilized to capture the relation among data objects, and the entire objects are represented as an edge-weighted graph where pairs of objects are connected with edges with their relevance. We show that, in hard assignment, the clustering problem can be approximated as a combinatorial problem over the proposed graph model when data is uniformly distributed. By representing the data objects as a graph based on our graph model, various graph based algorithms can be utilized to solve the clustering problem over the graph. The proposed approach is evaluated on the text clustering problem over 20 Newsgroup and TREC datasets. The results are encouraging and indicate the effectiveness of our approach.     

A novel attribute weighting algorithm for clustering high-dimensional categorical data

Due to data sparseness and attribute redundancy in high-dimensional data, clusters of objects often exist in subspaces rather than in the entire space. To effectively address this issue, this paper presents a new optimization algorithm for clustering high-dimensional categorical data, which is an extension of the k-modes clustering algorithm. In the proposed algorithm, a novel weighting technique for categorical data is developed to calculate two weights for each attribute (or dimension) in each cluster and use the weight values to identify the subsets of important attributes that categorize different clusters. The convergence of the algorithm under an optimization framework is proved. The performance and scalability of the algorithm is evaluated experimentally on both synthetic and real data sets. The experimental studies show that the proposed algorithm is effective in clustering categorical data sets and also scalable to large data sets owning to its linear time complexity with respect to the number of data objects, attributes or clusters.     

基于k-prototypes的混合属性数据聚类算法

通过对基于K-prototypes算法对混合属性数据处理的聚类问题进行研究,改进了K-prototypes算法中分类属性相异度计算公式,使之能更加精确反映样本间的差异;在此基础上提出了一种用于处理混合属性数据的聚类算法,并将改进后的算法应用于英语借词数据的聚类分析中。实验结果表明,与K-prototypes算法相比,改进后的算法具有更好的稳定性和更高的精度。     

一种基于信任值的分类属性聚类算法

针对K—Modes算法的不足,提出了一种基于信任值的分类属性聚类算法TrustCCluster,该算法不需预先给定聚类个数,聚类结果稳定且不依赖于初始值的选取。在真实数据上验证了TrustC—Cluster聚类算法,并与K—Modes和P—Modes算法进行了对比,实验结果表明TmstCCluster算法是有效、可行的。     

MMR: An algorithm for clustering categorical data using Rough Set Theory

A variety of cluster analysis techniques exist to group objects having similar characteristics. However, the implementation of many of these techniques is challenging due to the fact that much of the data contained in today’s databases is categorical in nature. While there have been recent advances in algorithms for clustering categorical data, some are unable to handle uncertainty in the clustering process while others have stability issues. This research proposes a new algorithm for clustering categorical data, termed Min–Min-Roughness (MMR), based on Rough Set Theory (RST), which has the ability to handle the uncertainty in the clustering process.     

MMR: An algorithm for clustering categorical data using Rough Set Theory

A variety of cluster analysis techniques exist to group objects having similar characteristics. However, the implementation of many of these techniques is challenging due to the fact that much of the data contained in today’s databases is categorical in nature. While there have been recent advances in algorithms for clustering categorical data, some are unable to handle uncertainty in the clustering process while others have stability issues. This research proposes a new algorithm for clustering categorical data, termed Min–Min-Roughness (MMR), based on Rough Set Theory (RST), which has the ability to handle the uncertainty in the clustering process.     

基于山方法的分类型数据核聚类

为了提高分类型数据集聚类的准确性和对广泛数据集聚类的适应性,引入3种核函数,再利用基于山方法的核K-means作分类型的数据聚类,核函数把分类型数据映射到高维特征空间,从而给缺乏测度的分类型数据引入了数值型数据的测度.改进后用多个公开数据集对这些方法进行了实验评测,结果显示这些方法对分类型数据的聚类是有效的.     

Novel dynamic k-modes clustering of categorical and non categorical dataset with optimized genetic algorithm based feature selection

Multimedia Tools and Applications - Clustering is a technique that segregates a provided dataset into homogenous groups in accordance with the provided features. It aims to determine a structure in...     

CPCQ: Contrast pattern based clustering quality index for categorical data

Clustering validation is concerned with assessing the quality of clustering solutions. Since clustering is unsupervised and highly explorative, clustering validation has been an important and long standing research problem. Existing validity measures, including entropy-based and distance-based indices, have significant shortcomings. Indeed, for many datasets from the UCI repository, they fail to recognize that the expert-determined classes are the best clusters and they frequently give preference to clusterings with larger number of clusters. Their weakness reflects their inability to accurately capture intra-cluster coherence and inter-cluster separation. This paper proposes a novel Contrast Pattern based Clustering Quality index (CPCQ) for categorical data, by utilizing the quality and diversity of the contrast patterns, which contrast the clusters in given clusterings. High quality contrast patterns can serve to characterize the clusters and discriminate one cluster against the others. The CPCQ index is based on the rationale that a high-quality clustering should have many diversified high-quality contrast patterns among its clusters. The quality of individual contrast patterns is defined in terms of their length, support, and the length of their corresponding closed pattern. The quality measure concerning “many diversified” contrast patterns is defined in terms of the quality and diversity of some selected groups of contrast patterns with minimal overlap among contrast patterns and groups in terms of items and matching transactions. Experiments show that the CPCQ index (1) does not require a user to provide a distance function; (2) does not give inappropriate preference to larger number of clusters; (3) can recognize that expert-determined classes are the best clusters for many datasets from the UCI repository.     

A cluster ensemble method for clustering categorical data

Categorical data clustering (CDC) and cluster ensemble (CE) have long been considered as separate research and application areas. The main focus of this paper is to investigate the commonalities between these two problems and the uses of these commonalities for the creation of new clustering algorithms for categorical data based on cross-fertilization between the two disjoint research fields. More precisely, we formally define the CDC problem as an optimization problem from the viewpoint of CE, and apply CE approach for clustering categorical data. Experimental results on real datasets show that CE based clustering method is competitive with existing CDC algorithms with respect to clustering accuracy.     

一种基于遗传算法的K-means聚类算法

传统K-means算法对初始聚类中心的选取和样本的输入顺序非常敏感,容易陷入局部最优。针对上述问题,提出了一种基于遗传算法的K-means聚类算法GKA,将K-means算法的局部寻优能力与遗传算法的全局寻优能力相结合,通过多次选择、交叉、变异的遗传操作,最终得到最优的聚类数和初始质心集,克服了传统K-means算法的局部性和对初始聚类中心的敏感性。