A Comparison of Cluster Algorithms and Distance ...

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A Comparison of Cluster Algorithms and Distance Measures for Time–Course Gene Expression Data Theresa Scharl1 1

Friedrich Leisch2

Institut f¨ ur Statistik und Wahrscheinlichkeitstheorie,Technische Universit¨ at Wien 2

Institut f¨ ur Statistik, Ludwig-Maximilians-Universit¨ at M¨ unchen Schloss Reisensburg “Statistical Computing” 2006

Overview • Motivation

• R Package flexclust

• Cluster Algorithms – k-Means – Quality Cluster Algorithm (QT-Clust)

• Distance Measures

• Simulation Study

Motivation Cluster techniques are commonly used in the analysis of gene expression data to • find co–regulated genes and • groups of genes with similar temporal or spatial expression patterns. We want to investigate the influence of the cluster methods used on the resulting clusters: • different cluster algorithms • various distance measures.

R Package flexclust • Flexible toolbox to investigate the influence of distance measures and cluster algorithms.

• Extensible implementations of the generalized k–means and QT– Clust algorithm.

• Possibility to try out a variety of distance or similarity measures.

• Cluster algorithms are treated separately from distance measures.

• Own distance functions can easily be implemented as distance measures.

R Package flexclust Function kcca uses a family concept similar to the implementation of generalized linear models in S(Chambers and Hastie, 1992). A KCCA family consists of the following two parts:

dist : A function taking N observations and K centroids as inputs and returning the N xK matrix of distances between all observations and centroids.

cent : An (optional) function computing the centroid for a given subset of the observations.

R Package flexclust An example for a new distance measure is given by distJackknife

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