image.py 文件源码

def img_to_graph(img, mask=None, return_as=sparse.coo_matrix, dtype=None):
    """Graph of the pixel-to-pixel gradient connections

    Edges are weighted with the gradient values.

    Read more in the :ref:`User Guide <image_feature_extraction>`.

    Parameters
    ----------
    img : ndarray, 2D or 3D
        2D or 3D image
    mask : ndarray of booleans, optional
        An optional mask of the image, to consider only part of the
        pixels.
    return_as : np.ndarray or a sparse matrix class, optional
        The class to use to build the returned adjacency matrix.
    dtype : None or dtype, optional
        The data of the returned sparse matrix. By default it is the
        dtype of img

    Notes
    -----
    For sklearn versions 0.14.1 and prior, return_as=np.ndarray was handled
    by returning a dense np.matrix instance.  Going forward, np.ndarray
    returns an np.ndarray, as expected.

    For compatibility, user code relying on this method should wrap its
    calls in ``np.asarray`` to avoid type issues.
    """
    img = np.atleast_3d(img)
    n_x, n_y, n_z = img.shape
    return _to_graph(n_x, n_y, n_z, mask, img, return_as, dtype)