B
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                 @   s(   d dl ZddlmZ ejd fddZdS )    N   )view_as_blocksc             C   s   t || jkrtdg }xltt |D ]\}|| dk r@td| j| ||  dkrr|| | j| ||   }nd}|d|f q(W tj| |d|d} t| |}x&tt |jd D ]}||dd	}qW |S )
aM  Down-sample image by applying function to local blocks.

    Parameters
    ----------
    image : ndarray
        N-dimensional input image.
    block_size : array_like
        Array containing down-sampling integer factor along each axis.
    func : callable
        Function object which is used to calculate the return value for each
        local block. This function must implement an ``axis`` parameter such
        as ``numpy.sum`` or ``numpy.min``.
    cval : float
        Constant padding value if image is not perfectly divisible by the
        block size.

    Returns
    -------
    image : ndarray
        Down-sampled image with same number of dimensions as input image.

    Examples
    --------
    >>> from skimage.measure import block_reduce
    >>> image = np.arange(3*3*4).reshape(3, 3, 4)
    >>> image # doctest: +NORMALIZE_WHITESPACE
    array([[[ 0,  1,  2,  3],
            [ 4,  5,  6,  7],
            [ 8,  9, 10, 11]],
           [[12, 13, 14, 15],
            [16, 17, 18, 19],
            [20, 21, 22, 23]],
           [[24, 25, 26, 27],
            [28, 29, 30, 31],
            [32, 33, 34, 35]]])
    >>> block_reduce(image, block_size=(3, 3, 1), func=np.mean)
    array([[[ 16.,  17.,  18.,  19.]]])
    >>> image_max1 = block_reduce(image, block_size=(1, 3, 4), func=np.max)
    >>> image_max1 # doctest: +NORMALIZE_WHITESPACE
    array([[[11]],
           [[23]],
           [[35]]])
    >>> image_max2 = block_reduce(image, block_size=(3, 1, 4), func=np.max)
    >>> image_max2 # doctest: +NORMALIZE_WHITESPACE
    array([[[27],
            [31],
            [35]]])
    z8`block_size` must have the same length as `image.shape`.   zYDown-sampling factors must be >= 1. Use `skimage.transform.resize` to up-sample an image.r   Zconstant)	pad_widthmodeZconstant_valuesr   )Zaxis)	lenndim
ValueErrorrangeshapeappendnpZpadr   )ZimageZ
block_sizefuncZcvalr   iZafter_widthout r   4lib/python3.7/site-packages/skimage/measure/block.pyblock_reduce   s     2

r   )Znumpyr   utilr   sumr   r   r   r   r   <module>   s   