Module « scipy.ndimage »

Fonction mean - module scipy.ndimage

Signature de la fonction mean

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

Description

mean.__doc__

    Calculate the mean of the values of an array at labels.

    Parameters
    ----------
    input : array_like
        Array on which to compute the mean of elements over distinct
        regions.
    labels : array_like, optional
        Array of labels of same shape, or broadcastable to the same shape as
        `input`. All elements sharing the same label form one region over
        which the mean of the elements is computed.
    index : int or sequence of ints, optional
        Labels of the objects over which the mean is to be computed.
        Default is None, in which case the mean for all values where label is
        greater than 0 is calculated.

    Returns
    -------
    out : list
        Sequence of same length as `index`, with the mean of the different
        regions labeled by the labels in `index`.

    See also
    --------
    variance, standard_deviation, minimum, maximum, sum, label

    Examples
    --------
    >>> from scipy import ndimage
    >>> a = np.arange(25).reshape((5,5))
    >>> labels = np.zeros_like(a)
    >>> labels[3:5,3:5] = 1
    >>> index = np.unique(labels)
    >>> labels
    array([[0, 0, 0, 0, 0],
           [0, 0, 0, 0, 0],
           [0, 0, 0, 0, 0],
           [0, 0, 0, 1, 1],
           [0, 0, 0, 1, 1]])
    >>> index
    array([0, 1])
    >>> ndimage.mean(a, labels=labels, index=index)
    [10.285714285714286, 21.0]