Perform centroid/UPGMC linkage.

See linkage for more information on the input matrix, return structure, and algorithm.

The following are common calling conventions:

  1. Z = centroid(y)

    Performs centroid/UPGMC linkage on the condensed distance matrix y.

  2. Z = centroid(X)

    Performs centroid/UPGMC linkage on the observation matrix X using Euclidean distance as the distance metric.

y : ndarray

A condensed distance matrix. A condensed distance matrix is a flat array containing the upper triangular of the distance matrix. This is the form that pdist returns. Alternatively, a collection of m observation vectors in n dimensions may be passed as a m by n array.

Z : ndarray

A linkage matrix containing the hierarchical clustering. See the linkage function documentation for more information on its structure.

See also

for advanced creation of hierarchical clusterings.