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Neural Network Homework Report: Clustering of the Self-Organizing Map. IEEE TRANSACTIONS ON NEURAL NETWORKS, VOL.11, NO.3, MAY 2000. Professor : Hahn-Ming Lee Student : Hsin-Chung Chen M9315928. OUTLINE. INTRODUCTION CLUSTERING SOM CLUSTERING EXPERIMENTS CONCLUSION.
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Neural Network Homework Report:Clustering of the Self-Organizing Map IEEE TRANSACTIONS ON NEURAL NETWORKS, VOL.11, NO.3, MAY 2000 Professor:Hahn-Ming Lee Student : Hsin-Chung Chen M9315928
OUTLINE • INTRODUCTION • CLUSTERING • SOM CLUSTERING • EXPERIMENTS • CONCLUSION
INTRODUCTION • DATA mining processes • problem definition • data acquisition. • data preprocessing and survey • data modeling • evaluation. • knowledge deployment. • Self-organization map feature: • Dimensionality reduction of unsupervised learning • Can applied in deal huge amounts of sample • The original data set is represented using a smaller set of prototype vectors • not to find an optimal clustering but to get good
CLUSTERING • two main ways approaches • hierarchical approaches • agglomerative algorithm: • bottom-up strategies to build a hierarchical clustering tree • divisive algorithm: • top-down strategies to build a hierarchical clustering tree • partitive approaches • k-means • optimal clustering is a partitioning • minimizes distances within • maximizes distances between clusters
SOM CLUSTERING • SOM training • first to find the best matching unit (BMU) • the prototype vectors are updated.
The SOM algorithm characteristic: • applicable to large data sets. • The computational complexity scales linearly with the number of data samples • it does not require huge amounts of memorythat basically just the prototype vectors and the current training vector .
EXPERIMENTS • Tools: SOM_ToolBox 2.0 : • Data set:clown.dat • Data set (“clown.data”) consisted of 2220 2-D samples. • cluster with three subclusters (right eye) • spherical cluster (left eye) • elliptical cluster (nose) • nonspherical cluster (U-shaped: mouth) • large and sparse cluster (body) • noise .(such as black x)
Methods and Parameters: • Cluster step 1: • Training Parameters of the SOM's • Map size: 19x17Initial Neighborhood Widths: Rough Phases σ1(0): 10 Fine-Tuning Phases σ2(0): 2learning rates:(The learning rate decreased linearly to zero during the training) Rough Phases : 0.5 Fine-Tuning Phases 0.05 • Cluster step 2: • Method: K-MeansUsing 100 Runs