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Fonction center_of_mass - module scipy.ndimage

Signature de la fonction center_of_mass

def center_of_mass(input, labels=None, index=None) 

Description

center_of_mass.__doc__

    Calculate the center of mass of the values of an array at labels.

    Parameters
    ----------
    input : ndarray
        Data from which to calculate center-of-mass. The masses can either
        be positive or negative.
    labels : ndarray, optional
        Labels for objects in `input`, as generated by `ndimage.label`.
        Only used with `index`. Dimensions must be the same as `input`.
    index : int or sequence of ints, optional
        Labels for which to calculate centers-of-mass. If not specified,
        all labels greater than zero are used. Only used with `labels`.

    Returns
    -------
    center_of_mass : tuple, or list of tuples
        Coordinates of centers-of-mass.

    Examples
    --------
    >>> a = np.array(([0,0,0,0],
    ...               [0,1,1,0],
    ...               [0,1,1,0],
    ...               [0,1,1,0]))
    >>> from scipy import ndimage
    >>> ndimage.measurements.center_of_mass(a)
    (2.0, 1.5)

    Calculation of multiple objects in an image

    >>> b = np.array(([0,1,1,0],
    ...               [0,1,0,0],
    ...               [0,0,0,0],
    ...               [0,0,1,1],
    ...               [0,0,1,1]))
    >>> lbl = ndimage.label(b)[0]
    >>> ndimage.measurements.center_of_mass(b, lbl, [1,2])
    [(0.33333333333333331, 1.3333333333333333), (3.5, 2.5)]

    Negative masses are also accepted, which can occur for example when
    bias is removed from measured data due to random noise.

    >>> c = np.array(([-1,0,0,0],
    ...               [0,-1,-1,0],
    ...               [0,1,-1,0],
    ...               [0,1,1,0]))
    >>> ndimage.measurements.center_of_mass(c)
    (-4.0, 1.0)

    If there are division by zero issues, the function does not raise an
    error but rather issues a RuntimeWarning before returning inf and/or NaN.

    >>> d = np.array([-1, 1])
    >>> ndimage.measurements.center_of_mass(d)
    (inf,)