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How to best perform cluster analysis on spiral data?

Hi,

 

I would like to know which clustering platform, available in either JMP or JMP Pro is best suited to identifying clusters from these spiral data.

 

 

Using HDBSCAN I can correctly identify the clusters as illustrated below but I would like to use JMP if possible:

 

 

Table script attached.

 

Thanks jpol

 

AnalyticsRe: How to best perform cluster analysis on spiral data?

Single linkage. You'll need to know how many clusters you want, 3 for example, or it will break the spiral arms into more.

Hierarchical Cluster(
    Y( :X, :Y ),
    Method( "Single" ),
    Standardize Data( 1 ),
    Color Clusters( 1 ),
    Dendrogram Scale( "Distance Scale" ),
    Number of Clusters( 3 )
)

Dendrogram with cluster colorsGraph with cluster colors

I think this article might help, I read just far enough to see it mentioned "chain".

https://stats.stackexchange.com/questions/195446/choosing-the-right-linkage-method-for-hierarchical-clustering

 

Re: How to best perform cluster analysis on spiral data?

Thanks Craig for indicating the correct method and the article link.

 

The Single Link method works very well on this relatively clean data set. 

 

The table script I provided above includes a script to add a few more rows of data, "Add Rows".

These should be considered as outliers, or at least be identified as not belonging to any of the three main clusters. Something like the  "-1" Cluster in HDBSCAN.

 

The addition of these extra points seems to play havoc with the single linkage method (when looking for 3 or 4 clusters).

Any idea how to avoid this?

 

   

 

 

- Philip

 

 

 

 

 

 

 

Re: How to best perform cluster analysis on spiral data?

I'm not the expert here; I'll defer to others. My guess would be a separate pass to discover points not that are further than average from other points, but that would fail if there were two outliers next to each other, so their cluster-of-two would need to be tested...perhaps the HDBSCAN is doing something like that.

 

Can you share what kind of process produces the spiral clusters?