Re: Re: Question - Cluster Analysis

• To: mathgroup at smc.vnet.net
• Subject: [mg89857] Re: [mg89842] Re: Question - Cluster Analysis
• From: DrMajorBob <drmajorbob at att.net>
• Date: Mon, 23 Jun 2008 02:45:55 -0400 (EDT)
• References: <g3ihn2\$fb6\$1@smc.vnet.net>

```That's a much nicer way to parse the Clusters. Thanks!

Bobby

On Sun, 22 Jun 2008 02:24:29 -0500, magma <maderri2 at gmail.com> wrote:

> On Jun 21, 11:30 am, Steve Mahoney <patrick.bernh... at gmx.net> wrote:
>> 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
>
> Hello,
> this was a good excuse for me to learn some cluster analysis in the
> past 2 hours !
> Ok, now I know what you are talking about, so this is your function
>
> ElbowCriterium[
>   cl_Cluster] := {cl[[3]], ElbowCriterium[cl[[1]]],
>    ElbowCriterium[cl[[2]]]} // Flatten
>
> ElbowCriterium[x_] := {}
>
>
> data = {{1, 2, 2}, {1, 3, 3}, {2, 4, 2}, {5, 4, 3}, {5, 4, 4}, {7, 6,
>     7}};
>
> Agglomerate[data] // ElbowCriterium
>
>
> {17, 10, 3, 2, 1}
>
>
>

--
DrMajorBob at longhorns.com

```

• Prev by Date: Re: FindROot and substitutions
• Next by Date: How to add a title to a cell and then collapse it?
• Previous by thread: Re: Question - Cluster Analysis
• Next by thread: Re: Looking for an example