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# scipy.cluster.hierarchy.num_obs_linkage

scipy.cluster.hierarchy.num_obs_linkage(Z)

  Return the number of original observations of the linkage matrix passed.

  Parameters:
    Z ndarray

      The linkage matrix on which to perform the operation.

  Returns:
    n int

      The number of original observations in the linkage.

  Examples

      >>> from scipy.cluster.hierarchy import ward, num_obs_linkage
      >>> from scipy.spatial.distance import pdist

      >>> X = [[0, 0], [0, 1], [1, 0],
      ...      [0, 4], [0, 3], [1, 4],
      ...      [4, 0], [3, 0], [4, 1],
      ...      [4, 4], [3, 4], [4, 3]]

      >>> Z = ward(pdist(X))

  `Z` is a linkage matrix obtained after using the Ward clustering method with `X`, a dataset with 12 data points.

      >>> num_obs_linkage(Z)
      12