改进K-均值聚类算法在电信客户分类中的应用

研究电信客户分类问题,根据不同类型采用不同策略.针对电信客户实行差异化营销和服务,需对电信客户进行准确分类.传统的k-均值聚类算法是一种重要数据挖掘技方法,存在对初始值敏感和易陷入局部最优的缺陷,导致电信客户分类正确率较低.为了提高电信客户分类的正确率,提出了一种改进k-均值聚类的电信客户分类算法.首先改进k-均值聚类算法通过变异、杂交和选择操作,然后根据分类特征动态地确定初始聚类数k和自适应确定聚类中心,最后采用湖南省某地区客户分类数据进行验证性实验.仿真结果表明,改进k-均值聚类算法很好地解决全局识别寻优问题,提高了客户分类正确率,大幅度减小误差.     

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.     

基于自适应特征权重聚类算法的用电问题分析

提升客服系统对于群体客户用电问题的分析与理解能力是改善电力行业客服质量的重要途径之一.本文基于数据挖掘中的聚类技术,以电力客服中心记录的客户用电问题为数据基础,建立客户服务数据分析聚类模型,进而提出了针对用电问题分析的改进的自适应特征权重K-Means聚类算法.实验验证了该方法可快速准确地实现客服数据的自动聚类,可挖掘出隐藏的客户用电问题关键信息,为改进用电力客服质量与潜在服务风险预测提供了技术支撑.     

优化初始聚类中心的改进k-means算法

传统k-means算法随机选取初始聚类中心使聚类结果不稳定,诸多优化算法的时间复杂度较高,为了提高聚类稳定性并降低时间复杂度,提出了基于个体轮廓系数自适应地选取优秀样本以确定初始聚类中心的改进k-means算法.该算法多次调用传统k-means算法聚类,根据k个类中心的个体轮廓系数以及各样本与类中心的距离,自适应地选取优秀样本,求其均值作为初始聚类中心.在多个UCI数据集上的实验表明,该算法聚类时间短,具有较高的轮廓系数和准确率.     

基于RFM模型的半监督聚类算法

客户分类作为客户关系管理（CRM）的重要管理方法,是企业进行市场营销的重要依据.通过对客户进行分类,有利于对客户价值进行准确评估,方便进行精准营销.本文通过对RFM模型数据集本身潜藏的先验结构化信息进行研究,标记出两组客户数据作为先验类别标记,进而得到两个初始聚类中心.基于传统K-means算法使用自适应方法确定K值和初始聚类中心.引入Must-link和Cannot-link两种约束将类别标记转换为成对约束信息,基于HMRF-KMeans成对约束,引入约束惩罚项和约束奖励项,实现对聚类引导和聚类结果的调整.使用改进的半监督聚类算法（RFM-SS-means）对标准数据集进行了测试,同时使用Food mart数据集对比了RFM-SS-means算法与传统K-means算法、two-steps算法的聚类效果.由实验结果可知,RFM-SS-means的CH系数最大,无需事先确定K值和初始聚类中心,聚类效果良好.     

基于自适应学习的演化聚类算法

演化聚类算法(ECM) 是一种有效的在线聚类算法, 能够根据输入数据实时调整聚类. 但是, 该聚类算法依赖于预先设置的最大距离阈值, 而且对数据输入次序敏感. 针对这些问题, 提出一种基于自适应学习的演化算法(SALECM), 在无法获取数据先验知识的情况下, 无需人为预先定义参数, 可自适应地调整聚类. 实验结果表明, 与 ECM相比, SALECM可提高在线聚类的自适应性能, 也能在一定程度上缓解数据输入次序对算法的影响.

     

基于核的自适应K—Medoid聚类

针对K-Medoid算法不能有效聚类大数据集和高维数据的弱点,将核学习方法引入到K-Medoid算法,提出了基于核的自适应K-Medoid算法.该算法利用核函数将输入空间样本映射到一个高维的特征空间,在这个核空间中进行K-Medoid聚类,在聚类过程中,数据可以自适应地加入到最适合它的簇当中,并且聚类结果与初始k个中心点的选取无关,该算法可以完成对大数据集和高维数据的聚类.实验结果表明,与K-Medoid算法相比,该算法具有较高的聚类准确率.     

一种基于增量式谱聚类的动态社区自适应发现算法

针对当前复杂网络动态社区发现的热点问题, 提出一种面向静态网络社区发现的链接相关线性谱聚类算法, 并在此基础上提出一种基于增量式谱聚类的动态社区自适应发现算法. 动态社区发现算法引入归一化图形拉普拉斯矩阵呈现复杂网络节点之间的关 系,采用拉普拉斯本征映射将节点投影到k维欧式空间.为解决离群节点影响谱聚类的效果和启发式确定复杂网络社区数量的问题, 利用提出的链接相关线性谱聚类算法发现初始时间片的社区结构, 使发现社区的过程能够以较低的时间开销自适应地挖掘复杂网络社区结构. 此后, 对于后续相邻的时间片, 提出的增量式谱聚类算法以前一时间片聚类获得的社区特征为基础, 通过调整链接相关线性谱聚类算法实现对后一时间片的增量聚类, 以达到自适应地发现复杂网络动态社区的目的. 在多个数据集的实验表明, 提出的链接相关线性谱聚类算法能够有效地检测出复杂网络中的社区结构以及基于 增量式谱聚类的动态社区自适应发现算法能够有效地挖掘网络中动态社区的演化过程.     

自适应仿射传播聚类

适合处理大类数的仿射传播聚类有两个尚未解决的问题: 一是很难确定偏向参数取何值能够使算法产生最优的聚类结果; 另一个是当震荡发生后算法不能自动消除震荡并收敛. 为了解决这两个问题, 提出了自适应仿射传播聚类方法, 具体技术包括: 自适应扫描偏向参数空间来搜索聚类个数空间以寻找最优聚类结果、自适应调整阻尼因子来消除震荡以及当调整阻尼因子方法失效时的自适应逃离震荡技术. 与原算法相比, 自适应仿射传播聚类方法性能更优, 能够自动消除震荡和寻找最优聚类结果. 对模拟和真实数据集的实验结果表明, 自适应仿射传播聚类方法十分有效, 其聚类质量优于或不低于原算法.     

基于改进DBSCAN算法的文本聚类

目前多数聚类算法不能很好地适应文本聚类的快速自适应需求。为此,论述DBSCAN算法的基本原理和实现过程,提出一种基于改进DBSCAN算法的文本聚类算法,利用最小二乘法降低文本向量的维度,并创建一种应用于DBSCAN算法的簇关系树结构。实验结果表明,该算法能自适应地进行文本聚类,且与DBSCAN相比,准确率较高。     

A novel clustering algorithm based on data transformation approaches

Clustering provides a knowledge acquisition method for intelligent systems. This paper proposes a novel data-clustering algorithm, by combining a new initialization technique, K-means algorithm and a new gradual data transformation approach to provide more accurate clustering results than the K-means algorithm and its variants by increasing the clusters’ coherence. The proposed data transformation approach solves the problem of generating empty clusters, which frequently occurs for other clustering algorithms. An efficient method based on the principal component transformation and a modified silhouette algorithm is also proposed in this paper to determine the number of clusters. Several different data sets are used to evaluate the efficacy of the proposed method to deal with the empty cluster generation problem and its accuracy and computational performance in comparison with other K-means based initialization techniques and clustering methods. The developed estimation method for determining the number of clusters is also evaluated and compared with other estimation algorithms. Significances of the proposed method include addressing the limitations of the K-means based clustering and improving the accuracy of clustering as an important method in the field of data mining and expert systems. Application of the proposed method for the knowledge acquisition in time series data such as wind, solar, electric load and stock market provides a pre-processing tool to select the most appropriate data to feed in neural networks or other estimators in use for forecasting such time series. In addition, utilization of the knowledge discovered by the proposed K-means clustering to develop rule based expert systems is one of the main impacts of the proposed method.     

A robust iterative refinement clustering algorithm with smoothing search space

Iterative refinement clustering algorithms are widely used in data mining area, but they are sensitive to the initialization. In the past decades, many modified initialization methods have been proposed to reduce the influence of initialization sensitivity problem. The essence of iterative refinement clustering algorithms is the local search method. The big numbers of the local minimum points which are embedded in the search space make the local search problem hard and sensitive to the initialization. The smaller number of local minimum points, the more robust of initialization for a local search algorithm is. In this paper, we propose a Top–Down Clustering algorithm with Smoothing Search Space (TDCS3) to reduce the influence of initialization. The main steps of TDCS3 are to: (1) dynamically reconstruct a series of smoothed search spaces into a hierarchical structure by ‘filling’ the local minimum points; (2) at the top level of the hierarchical structure, an existing iterative refinement clustering algorithm is run with random initialization to generate the clustering result; (3) eventually from the second level to the bottom level of the hierarchical structure, the same clustering algorithm is run with the initialization derived from the previous clustering result. Experiment results on 3 synthetic and 10 real world data sets have shown that TDCS3 has significant effects on finding better, robust clustering result and reducing the impact of initialization.     

初始化独立的谱聚类算法

谱聚类作为一种新颖的聚类算法近年来受到模式识别领域的广泛关注。针对传统谱聚类算法对初始中心敏感的特点,通过引入对初值不敏感的k-调和平均算法,提出一种初始化独立的谱聚类算法。在人工数据和真实数据上的实验表明,相比于传统的k-means算法、FCM算法和EM算法,改进算法在稳定性和聚类性能上有了显著的提高。     

利用FCM求解最佳聚类数的算法

利用FCM求解最佳聚类数的算法中,每次应用FCM算法都要重新初始化类中心,而FCM算法对初始类中心敏感,这样使得利用FCM求解最佳聚类数的算法很不稳定。对该算法进行了改进,提出了一个合并函数,使得（c－1）类的类中心依赖于类的类中心。仿真实验表明：新的算法稳定性好,且运算速度明显比旧的算法要快。     

A robust EM clustering algorithm for Gaussian mixture models

Clustering is a useful tool for finding structure in a data set. The mixture likelihood approach to clustering is a popular clustering method, in which the EM algorithm is the most used method. However, the EM algorithm for Gaussian mixture models is quite sensitive to initial values and the number of its components needs to be given a priori. To resolve these drawbacks of the EM, we develop a robust EM clustering algorithm for Gaussian mixture models, first creating a new way to solve these initialization problems. We then construct a schema to automatically obtain an optimal number of clusters. Therefore, the proposed robust EM algorithm is robust to initialization and also different cluster volumes with automatically obtaining an optimal number of clusters. Some experimental examples are used to compare our robust EM algorithm with existing clustering methods. The results demonstrate the superiority and usefulness of our proposed method.     

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.     

A cluster centers initialization method for clustering categorical data

The leading partitional clustering technique, k-modes, is one of the most computationally efficient clustering methods for categorical data. However, the performance of the k-modes clustering algorithm which converges to numerous local minima strongly depends on initial cluster centers. Currently, most methods of initialization cluster centers are mainly for numerical data. Due to lack of geometry for the categorical data, these methods used in cluster centers initialization for numerical data are not applicable to categorical data. This paper proposes a novel initialization method for categorical data which is implemented to the k-modes algorithm. The method integrates the distance and the density together to select initial cluster centers and overcomes shortcomings of the existing initialization methods for categorical data. Experimental results illustrate the proposed initialization method is effective and can be applied to large data sets for its linear time complexity with respect to the number of data objects.     

K-Harmonic means type clustering algorithm for mixed datasets

K-means type clustering algorithms for mixed data that consists of numeric and categorical attributes suffer from cluster center initialization problem. The final clustering results depend upon the initial cluster centers. Random cluster center initialization is a popular initialization technique. However, clustering results are not consistent with different cluster center initializations. K-Harmonic means clustering algorithm tries to overcome this problem for pure numeric data. In this paper, we extend the K-Harmonic means clustering algorithm for mixed datasets. We propose a definition for a cluster center and a distance measure. These cluster centers and the distance measure are used with the cost function of K-Harmonic means clustering algorithm in the proposed algorithm. Experiments were carried out with pure categorical datasets and mixed datasets. Results suggest that the proposed clustering algorithm is quite insensitive to the cluster center initialization problem. Comparative studies with other clustering algorithms show that the proposed algorithm produce better clustering results.     

基于Hub的高维数据初始聚类中心的选择策略

针对基于Hub的聚类算法K-hubs算法存在对初始聚类中心敏感的问题,提出一种基于Hub的初始中心选择策略。该策略充分利用高维数据普遍存在的Hubness现象,选择相距最远的K个Hub点作为初始的聚类中心。实验表明采用该策略的K-hubs算法与原来采用随机初始中心的K-hubs算法相比,前者拥有较好的初始中心分布,能够提高聚类准确率,而且初始中心所在的位置倾向于接近最终簇中心,有利于加快算法收敛。     

Soft clustering using weighted one-class support vector machines

This paper describes a new soft clustering algorithm in which each cluster is modelled by a one-class support vector machine (OC-SVM). The proposed algorithm extends a previously proposed hard clustering algorithm, also based on OC-SVM representation of clusters. The key building block of our method is the weighted OC-SVM (WOC-SVM), a novel tool introduced in this paper, based on which an expectation-maximization-type soft clustering algorithm is defined. A deterministic annealing version of the algorithm is also introduced, and shown to improve the robustness with respect to initialization. Experimental results show that the proposed soft clustering algorithm outperforms its hard clustering counterpart, namely in terms of robustness with respect to initialization, as well as several other state-of-the-art methods.