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Preview Data Mining and Analysis: Fundamental Concepts and Algorithms

Data Mining and Analysis: Fundamental Concepts and Algorithms Mohammed J. Zaki Wagner Meira Jr. CONTENTS i Contents Preface 1 1 Data Mining and Analysis 4 1.1 Data Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3 Data: Algebraic and Geometric View . . . . . . . . . . . . . . . . . . 7 1.3.1 Distance and Angle . . . . . . . . . . . . . . . . . . . . . . . . 9 1.3.2 Mean and Total Variance . . . . . . . . . . . . . . . . . . . . 13 1.3.3 Orthogonal Projection . . . . . . . . . . . . . . . . . . . . . . 14 1.3.4 Linear Independence and Dimensionality . . . . . . . . . . . . 15 1.4 Data: Probabilistic View . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.4.1 Bivariate Random Variables . . . . . . . . . . . . . . . . . . . 24 1.4.2 Multivariate Random Variable . . . . . . . . . . . . . . . . . 28 1.4.3 Random Sample and Statistics . . . . . . . . . . . . . . . . . 29 1.5 Data Mining. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 1.5.1 Exploratory Data Analysis. . . . . . . . . . . . . . . . . . . . 31 1.5.2 Frequent Pattern Mining . . . . . . . . . . . . . . . . . . . . . 33 1.5.3 Clustering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1.5.4 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1.6 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 1.7 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 I Data Analysis Foundations 37 2 Numeric Attributes 38 2.1 Univariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.1.1 Measures of Central Tendency . . . . . . . . . . . . . . . . . . 39 2.1.2 Measures of Dispersion . . . . . . . . . . . . . . . . . . . . . . 43 2.2 Bivariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 2.2.1 Measures of Location and Dispersion . . . . . . . . . . . . . . 49 2.2.2 Measures of Association . . . . . . . . . . . . . . . . . . . . . 50 CONTENTS ii 2.3 Multivariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 2.4 Data Normalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 2.5 Normal Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 2.5.1 Univariate Normal Distribution . . . . . . . . . . . . . . . . . 61 2.5.2 Multivariate Normal Distribution . . . . . . . . . . . . . . . . 63 2.6 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 2.7 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 3 Categorical Attributes 71 3.1 Univariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 3.1.1 Bernoulli Variable . . . . . . . . . . . . . . . . . . . . . . . . 71 3.1.2 Multivariate Bernoulli Variable . . . . . . . . . . . . . . . . . 74 3.2 Bivariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 3.2.1 Attribute Dependence: Contingency Analysis . . . . . . . . . 88 3.3 Multivariate Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 3.3.1 Multi-way Contingency Analysis . . . . . . . . . . . . . . . . 95 3.4 Distance and Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 3.5 Discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 3.6 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 3.7 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 4 Graph Data 105 4.1 Graph Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 4.2 Topological Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . 110 4.3 Centrality Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 4.3.1 Basic Centralities . . . . . . . . . . . . . . . . . . . . . . . . . 115 4.3.2 Web Centralities . . . . . . . . . . . . . . . . . . . . . . . . . 117 4.4 Graph Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 4.4.1 Erdös-Rényi Random Graph Model . . . . . . . . . . . . . . . 129 4.4.2 Watts-Strogatz Small-world Graph Model . . . . . . . . . . . 133 4.4.3 Barabási-Albert Scale-free Model . . . . . . . . . . . . . . . . 139 4.5 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 4.6 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 5 Kernel Methods 150 5.1 Kernel Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 5.1.1 Reproducing Kernel Map . . . . . . . . . . . . . . . . . . . . 156 5.1.2 Mercer Kernel Map . . . . . . . . . . . . . . . . . . . . . . . . 158 5.2 Vector Kernels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 5.3 Basic Kernel Operations in Feature Space . . . . . . . . . . . . . . . 166 5.4 Kernels for Complex Objects . . . . . . . . . . . . . . . . . . . . . . 173 5.4.1 Spectrum Kernel for Strings . . . . . . . . . . . . . . . . . . . 173 5.4.2 Diffusion Kernels on Graph Nodes . . . . . . . . . . . . . . . 175 CONTENTS iii 5.5 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 5.6 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 6 High-Dimensional Data 182 6.1 High-Dimensional Objects . . . . . . . . . . . . . . . . . . . . . . . . 182 6.2 High-Dimensional Volumes . . . . . . . . . . . . . . . . . . . . . . . . 184 6.3 Hypersphere Inscribed within Hypercube . . . . . . . . . . . . . . . . 187 6.4 Volume of Thin Hypersphere Shell . . . . . . . . . . . . . . . . . . . 189 6.5 Diagonals in Hyperspace . . . . . . . . . . . . . . . . . . . . . . . . . 190 6.6 Density of the Multivariate Normal . . . . . . . . . . . . . . . . . . . 191 6.7 Appendix: Derivation of Hypersphere Volume . . . . . . . . . . . . . 195 6.8 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 6.9 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 7 Dimensionality Reduction 204 7.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 7.2 Principal Component Analysis. . . . . . . . . . . . . . . . . . . . . . 209 7.2.1 Best Line Approximation . . . . . . . . . . . . . . . . . . . . 209 7.2.2 Best Two-dimensional Approximation . . . . . . . . . . . . . 213 7.2.3 Best r-dimensional Approximation . . . . . . . . . . . . . . . 217 7.2.4 Geometry of PCA . . . . . . . . . . . . . . . . . . . . . . . . 222 7.3 Kernel Principal Component Analysis (Kernel PCA) . . . . . . . . . 225 7.4 Singular Value Decomposition . . . . . . . . . . . . . . . . . . . . . . 233 7.4.1 Geometry of SVD . . . . . . . . . . . . . . . . . . . . . . . . 234 7.4.2 Connection between SVD and PCA. . . . . . . . . . . . . . . 235 7.5 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 7.6 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 II Frequent Pattern Mining 240 8 Itemset Mining 241 8.1 Frequent Itemsets and Association Rules . . . . . . . . . . . . . . . . 241 8.2 Itemset Mining Algorithms . . . . . . . . . . . . . . . . . . . . . . . 245 8.2.1 Level-Wise Approach: Apriori Algorithm . . . . . . . . . . . 247 8.2.2 Tidset Intersection Approach: Eclat Algorithm . . . . . . . . 250 8.2.3 Frequent Pattern Tree Approach: FPGrowth Algorithm . . . 256 8.3 Generating Association Rules . . . . . . . . . . . . . . . . . . . . . . 260 8.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 8.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 CONTENTS iv 9 Summarizing Itemsets 269 9.1 Maximal and Closed Frequent Itemsets . . . . . . . . . . . . . . . . . 269 9.2 Mining Maximal Frequent Itemsets: GenMax Algorithm . . . . . . . 273 9.3 Mining Closed Frequent Itemsets: Charm algorithm . . . . . . . . . 275 9.4 Non-Derivable Itemsets. . . . . . . . . . . . . . . . . . . . . . . . . . 278 9.5 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 9.6 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 10 Sequence Mining 289 10.1 Frequent Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 10.2 Mining Frequent Sequences . . . . . . . . . . . . . . . . . . . . . . . 290 10.2.1 Level-Wise Mining: GSP . . . . . . . . . . . . . . . . . . . . . 292 10.2.2 Vertical Sequence Mining: SPADE . . . . . . . . . . . . . . . 293 10.2.3 Projection-Based Sequence Mining: PrefixSpan . . . . . . . . 296 10.3 Substring Mining via Suffix Trees . . . . . . . . . . . . . . . . . . . . 298 10.3.1 Suffix Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 10.3.2 Ukkonen’s Linear Time Algorithm . . . . . . . . . . . . . . . 301 10.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309 10.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309 11 Graph Pattern Mining 314 11.1 Isomorphism and Support . . . . . . . . . . . . . . . . . . . . . . . . 314 11.2 Candidate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . 318 11.2.1 Canonical Code . . . . . . . . . . . . . . . . . . . . . . . . . . 320 11.3 The gSpan Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . 323 11.3.1 Extension and Support Computation . . . . . . . . . . . . . . 326 11.3.2 Canonicality Checking . . . . . . . . . . . . . . . . . . . . . . 330 11.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 11.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 12 Pattern and Rule Assessment 337 12.1 Rule and Pattern Assessment Measures . . . . . . . . . . . . . . . . 337 12.1.1 Rule Assessment Measures . . . . . . . . . . . . . . . . . . . . 338 12.1.2 Pattern Assessment Measures . . . . . . . . . . . . . . . . . . 346 12.1.3 Comparing Multiple Rules and Patterns . . . . . . . . . . . . 349 12.2 Significance Testing and Confidence Intervals . . . . . . . . . . . . . 354 12.2.1 Fisher Exact Test for Productive Rules . . . . . . . . . . . . . 354 12.2.2 Permutation Test for Significance . . . . . . . . . . . . . . . . 359 12.2.3 Bootstrap Sampling for Confidence Interval . . . . . . . . . . 364 12.3 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367 12.4 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 CONTENTS v III Clustering 370 13 Representative-based Clustering 371 13.1 K-means Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372 13.2 Kernel K-means . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375 13.3 Expectation Maximization (EM) Clustering . . . . . . . . . . . . . . 381 13.3.1 EM in One Dimension . . . . . . . . . . . . . . . . . . . . . . 383 13.3.2 EM in d-Dimensions . . . . . . . . . . . . . . . . . . . . . . . 386 13.3.3 Maximum Likelihood Estimation . . . . . . . . . . . . . . . . 393 13.3.4 Expectation-Maximization Approach . . . . . . . . . . . . . . 397 13.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 13.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 14 Hierarchical Clustering 404 14.1 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404 14.2 Agglomerative Hierarchical Clustering . . . . . . . . . . . . . . . . . 407 14.2.1 Distance between Clusters . . . . . . . . . . . . . . . . . . . . 407 14.2.2 Updating Distance Matrix . . . . . . . . . . . . . . . . . . . . 411 14.2.3 Computational Complexity . . . . . . . . . . . . . . . . . . . 413 14.3 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413 14.4 Exercises and Projects . . . . . . . . . . . . . . . . . . . . . . . . . . 414 15 Density-based Clustering 417 15.1 The DBSCAN Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 418 15.2 Kernel Density Estimation . . . . . . . . . . . . . . . . . . . . . . . . 421 15.2.1 Univariate Density Estimation . . . . . . . . . . . . . . . . . 422 15.2.2 Multivariate Density Estimation . . . . . . . . . . . . . . . . 424 15.2.3 Nearest Neighbor Density Estimation . . . . . . . . . . . . . . 427 15.3 Density-based Clustering: DENCLUE . . . . . . . . . . . . . . . . . 428 15.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434 15.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434 16 Spectral and Graph Clustering 438 16.1 Graphs and Matrices . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 16.2 Clustering as Graph Cuts . . . . . . . . . . . . . . . . . . . . . . . . 446 16.2.1 Clustering Objective Functions: Ratio and Normalized Cut . 448 16.2.2 Spectral Clustering Algorithm . . . . . . . . . . . . . . . . . . 451 16.2.3 Maximization Objectives: Average Cut and Modularity. . . . 455 16.3 Markov Clustering . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463 16.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 470 16.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471 CONTENTS vi 17 Clustering Validation 473 17.1 External Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474 17.1.1 Matching Based Measures . . . . . . . . . . . . . . . . . . . . 474 17.1.2 Entropy Based Measures . . . . . . . . . . . . . . . . . . . . . 479 17.1.3 Pair-wise Measures . . . . . . . . . . . . . . . . . . . . . . . . 482 17.1.4 Correlation Measures . . . . . . . . . . . . . . . . . . . . . . . 486 17.2 Internal Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 489 17.3 Relative Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498 17.3.1 Cluster Stability . . . . . . . . . . . . . . . . . . . . . . . . . 505 17.3.2 Clustering Tendency . . . . . . . . . . . . . . . . . . . . . . . 508 17.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513 17.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514 IV Classification 516 18 Probabilistic Classification 517 18.1 Bayes Classifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517 18.1.1 Estimating the Prior Probability . . . . . . . . . . . . . . . . 518 18.1.2 Estimating the Likelihood . . . . . . . . . . . . . . . . . . . . 518 18.2 Naive Bayes Classifier . . . . . . . . . . . . . . . . . . . . . . . . . . 524 18.3 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528 18.4 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528 19 Decision Tree Classifier 530 19.1 Decision Trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532 19.2 Decision Tree Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . 535 19.2.1 Split-point Evaluation Measures . . . . . . . . . . . . . . . . 536 19.2.2 Evaluating Split-points . . . . . . . . . . . . . . . . . . . . . . 537 19.2.3 Computational Complexity . . . . . . . . . . . . . . . . . . . 545 19.3 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 546 19.4 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 547 20 Linear Discriminant Analysis 549 20.1 Optimal Linear Discriminant . . . . . . . . . . . . . . . . . . . . . . 549 20.2 Kernel Discriminant Analysis . . . . . . . . . . . . . . . . . . . . . . 556 20.3 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564 20.4 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564 21 Support Vector Machines 566 21.1 Linear Discriminants and Margins . . . . . . . . . . . . . . . . . . . 566 21.2 SVM: Linear and Separable Case . . . . . . . . . . . . . . . . . . . . 572 21.3 Soft Margin SVM: Linear and Non-Separable Case . . . . . . . . . . 577 CONTENTS vii 21.3.1 Hinge Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578 21.3.2 Quadratic Loss . . . . . . . . . . . . . . . . . . . . . . . . . . 582 21.4 Kernel SVM: Nonlinear Case . . . . . . . . . . . . . . . . . . . . . . 583 21.5 SVM Training Algorithms . . . . . . . . . . . . . . . . . . . . . . . . 588 21.5.1 Dual Solution: Stochastic Gradient Ascent . . . . . . . . . . . 588 21.5.2 Primal Solution: Newton Optimization . . . . . . . . . . . . . 593 22 Classification Assessment 602 22.1 Classification Performance Measures . . . . . . . . . . . . . . . . . . 602 22.1.1 Contingency Table Based Measures . . . . . . . . . . . . . . . 604 22.1.2 Binary Classification: Positive and Negative Class . . . . . . 607 22.1.3 ROC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 22.2 Classifier Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . 616 22.2.1 K-fold Cross-Validation . . . . . . . . . . . . . . . . . . . . . 617 22.2.2 Bootstrap Resampling . . . . . . . . . . . . . . . . . . . . . . 618 22.2.3 Confidence Intervals . . . . . . . . . . . . . . . . . . . . . . . 620 22.2.4 Comparing Classifiers: Paired t-Test . . . . . . . . . . . . . . 625 22.3 Bias-Variance Decomposition . . . . . . . . . . . . . . . . . . . . . . 627 22.3.1 Ensemble Classifiers . . . . . . . . . . . . . . . . . . . . . . . 632 22.4 Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 638 22.5 Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639 Index 641 CONTENTS 1 Preface ThisbookisanoutgrowthofdataminingcoursesatRPIandUFMG;theRPIcourse has been offered every Fall since 1998, whereas the UFMG course has been offered since 2002. While there are several good books on data mining and related topics, we felt that many of them are either too high-level or too advanced. Our goal was to write an introductory text which focuses on the fundamental algorithms in data mining and analysis. It lays the mathematical foundations for the core data mining methods, with key concepts explained when first encountered; the book also tries to build the intuition behind the formulas to aid understanding. The main parts of the book include exploratory data analysis, frequent pattern mining, clustering and classification. The book lays the basic foundations of these tasks, and it also covers cutting edge topics like kernel methods, high dimensional data analysis, and complex graphs and networks. It integrates concepts from related disciplines like machine learning and statistics, and is also ideal for a course on data analysis. Mostof the prerequisite material is covered in the text, especially on linear algebra, and probability and statistics. The book includes many examples to illustrate the main technical concepts. It alsohasendofchapterexercises,whichhavebeenusedinclass. Allofthealgorithms in the book have been implemented by the authors. We suggest that the reader use their favorite data analysis and mining software to work through our examples, and to implement the algorithms we describe in text; we recommend the R software, or the Python language with its NumPy package. The datasets used and other supplementary material like project ideas, slides, and so on, are available online at the book’s companion site and its mirrors at RPI and UFMG http://dataminingbook.info • http://www.cs.rpi.edu/~zaki/dataminingbook • http://www.dcc.ufmg.br/dataminingbook • Having understood the basic principles and algorithms in data mining and data analysis, the readers will bewell equipped todevelop their own methods or usemore advanced techniques. CONTENTS 2 Suggested Roadmaps The chapter dependency graph is shown in Figure 1. We suggest some typical roadmaps for courses and readings based on this book. For an undergraduate level course, we suggest the following chapters: 1-3, 8, 10, 12-15, 17-19, and 21-22. For an undergraduate course without exploratory data analysis, we recommend Chapters 1, 8-15, 17-19, and 21-22. For a graduate course, one possibility is to quickly go over the material in Part I, or to assume it as background reading and to directly cover Chapters 9-23; the other parts of the book, namely frequent pattern mining (Part II), clustering (Part III), and classification (Part IV) can be covered in any order. Foracourseondataanalysisthechaptersmustinclude1-7, 13-14,15(Section 2), and 20. Finally, for a course with an emphasis on graphs and kernels we suggest Chapters 4, 5, 7 (Sections 1-3), 11-12, 13 (Sections 1-2), 16-17, 20-22. 1 2 3 14 6 7 15 5 4 19 18 8 13 16 20 21 11 9 10 17 22 12 Figure 1: Chapter Dependencies Acknowledgments Initial drafts of this book have been used in many data mining courses. We received many valuable comments and corrections from both the faculty and students. Our thanks go to Muhammad Abulaish, Jamia Millia Islamia, India •

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