Question - Cluster Analysis

• To: mathgroup at smc.vnet.net
• Subject: [mg89805] Question - Cluster Analysis
• From: Steve Mahoney <patrick.bernhard at gmx.net>
• Date: Sat, 21 Jun 2008 05:29:23 -0400 (EDT)

```Hello,

I have a question regarding hierarchical cluster analysis. One measure to determine the number of clusters is the so called elbow criteria, which is just a list of the single distances between the clusters.

These values are inside the results from the Agglomerate function, but I am not able to extract them to a list.

data = {{1, 2, 2}, {1, 3, 3}, {2, 4, 2}, {5, 4, 3}, {5, 4, 4}, {7, 6, 7}};

Agglomerate[data]

Cluster[Cluster[
Cluster[Cluster[{1, 2, 2}, {1, 3, 3}, 2, 1, 1], {2, 4, 2}, 3, 2, 1], Cluster[{5, 4, 3}, {5, 4, 4}, 1, 1, 1], 10, 3, 2], {7, 6, 7}, 17, 5, 1]

--> now I have to extract the values manually

elbowcriterium = ListLinePlot[{17, 10, 3, 2, 1}]

--> suggesting three clusters

Thanks a lot for a suggestion, how to handle this, which would be really helpful for me!

```

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