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# Didacticiel Etudes de cas R R

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8 pages
English
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Niveau: Supérieur, Doctorat, Bac+8
Didacticiel - Etudes de cas R.R. 03/09/2006 Page 1 sur 8 Subject Gaussian mixture model based clustering with TANAGRA: the EM algorithm. In the Gaussian mixture model-based clustering, each cluster is represented by a Gaussian distribution. The entire dataset is modeled by a mixture (a linear combination) of these distributions. The EM (Expectation Maximization) algorithm is used in practice to find the “optimal” parameters of the distributions that maximize the likelihood function. The number of clusters is a parameter of the algorithm. But we can also detect the “optimal” number of clusters by evaluating several values, i.e. testing 1 cluster, 2 clusters, etc. and choosing the best one (which maximizes the likelihood or another criterion such as AIC or BIC). Dataset We use a synthetic dataset in a two dimensional space1. We aim to discover two clusters (Figure 1). Figure 1: Two Gaussian with different parameters (means and shapes – covariance matrices) 1 This dataset comes from the free distribution of « FAST EM Clustering » (AUTONLAB --

• clustering tab

• mixture model

• model-based clustering

• fast em

• em algorithm

• subject gaussian

• gaussian mixture

Sujets

##### Expectation-maximization algorithm

Informations

 Publié par profil-zyak-2012 Nombre de lectures 11 Langue English

Extrait

Didacticiel - Etudes de cas
Subject
R.R.
Gaussian mixture model based clustering with TANAGRA: the EM algorithm. In theGaussian mixture model-based clustering, each cluster is represented by a Gaussian distribution. The entire dataset is modeled by a mixture (a linear combination) of these distributions. TheEM (Expectation Maximization) algorithmused in practice to find the “optimal” is parameters of the distributions that maximize the likelihood function. The number of clusters is a parameter of the algorithm. But we can also detect the “optimal” number of clusters by evaluating several values, i.e. testing 1 cluster, 2 clusters, etc. and choosing the best one (which maximizes the likelihood or another criterion such as AIC or BIC).
Dataset
1 We use a synthetic dataset in a two dimensional space . We aim to discover two clusters (Figure 1).
Figure 1: Two Gaussian with different parameters (means and shapes – covariance matrices)
1 This dataset comes from the free distribution of « FAST EM http://www.autonlab.org/autonweb/10466.html).
03/09/2006
Clustering » (AUTONLAB --
Page 1 sur 8
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