Module « scipy.cluster.hierarchy »

Fonction from_mlab_linkage - module scipy.cluster.hierarchy

Signature de la fonction from_mlab_linkage

def from_mlab_linkage(Z) 

Description

from_mlab_linkage.__doc__

    Convert a linkage matrix generated by MATLAB(TM) to a new
    linkage matrix compatible with this module.

    The conversion does two things:

     * the indices are converted from ``1..N`` to ``0..(N-1)`` form,
       and

     * a fourth column ``Z[:,3]`` is added where ``Z[i,3]`` represents the
       number of original observations (leaves) in the non-singleton
       cluster ``i``.

    This function is useful when loading in linkages from legacy data
    files generated by MATLAB.

    Parameters
    ----------
    Z : ndarray
        A linkage matrix generated by MATLAB(TM).

    Returns
    -------
    ZS : ndarray
        A linkage matrix compatible with ``scipy.cluster.hierarchy``.

    See Also
    --------
    linkage : for a description of what a linkage matrix is.
    to_mlab_linkage : transform from SciPy to MATLAB format.

    Examples
    --------
    >>> import numpy as np
    >>> from scipy.cluster.hierarchy import ward, from_mlab_linkage

    Given a linkage matrix in MATLAB format ``mZ``, we can use
    `scipy.cluster.hierarchy.from_mlab_linkage` to import
    it into SciPy format:

    >>> mZ = np.array([[1, 2, 1], [4, 5, 1], [7, 8, 1],
    ...                [10, 11, 1], [3, 13, 1.29099445],
    ...                [6, 14, 1.29099445],
    ...                [9, 15, 1.29099445],
    ...                [12, 16, 1.29099445],
    ...                [17, 18, 5.77350269],
    ...                [19, 20, 5.77350269],
    ...                [21, 22,  8.16496581]])

    >>> Z = from_mlab_linkage(mZ)
    >>> Z
    array([[  0.        ,   1.        ,   1.        ,   2.        ],
           [  3.        ,   4.        ,   1.        ,   2.        ],
           [  6.        ,   7.        ,   1.        ,   2.        ],
           [  9.        ,  10.        ,   1.        ,   2.        ],
           [  2.        ,  12.        ,   1.29099445,   3.        ],
           [  5.        ,  13.        ,   1.29099445,   3.        ],
           [  8.        ,  14.        ,   1.29099445,   3.        ],
           [ 11.        ,  15.        ,   1.29099445,   3.        ],
           [ 16.        ,  17.        ,   5.77350269,   6.        ],
           [ 18.        ,  19.        ,   5.77350269,   6.        ],
           [ 20.        ,  21.        ,   8.16496581,  12.        ]])

    As expected, the linkage matrix ``Z`` returned includes an
    additional column counting the number of original samples in
    each cluster. Also, all cluster indices are reduced by 1
    (MATLAB format uses 1-indexing, whereas SciPy uses 0-indexing).