how to find out the content of one cluster
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KnowledgeSeeker
le 24 Fév 2014
Réponse apportée : Walter Roberson
le 24 Fév 2014
I have multiple clusters and I am concerning how to find the features of each cluster. Is there any way that allows me to find the cluster's content or features and what features are in the cluster.
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Walter Roberson
le 24 Fév 2014
Not really, no. Clusters, especially as determined by k-means, do not have "features". The k-means documentation indicates,
This iterative partitioning minimizes the sum, over all clusters, of the within-cluster sums of point-to-cluster-centroid distances. Rows of X correspond to points, columns correspond to variables.
If you were working with two variables (two columns) then a geometric interpretation would be that any given point P is considered to be associated with a centroid C if the circle of radius |PQ| around P does not (strictly) include any other centroid.
Likewise you can extend to three variables (three columns) and extend the geometric interpretation to be "sphere" instead of "circle".
You can see, then, that the cluster associated with C does not have any particular value or even value range for the variables. The boundary between clusters would be the intersection of hyperspheres around the centroids.
If you were using SVM, and you had only two clusters, then you could find a hyperplane that divided the two clusters -- but a hyperplane is not what one would typically think of as being a "feature".
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