scikit-image

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import numpy as np
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from . import draw
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def polygon2mask(image_shape, polygon):
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    """Create a binary mask from a polygon.
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    Parameters
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    ----------
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    image_shape : tuple of size 2
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        The shape of the mask.
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    polygon : (N, 2) array_like
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        The polygon coordinates of shape (N, 2) where N is
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        the number of points. The coordinates are (row, column).
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    Returns
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    -------
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    mask : 2-D ndarray of type 'bool'
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        The binary mask that corresponds to the input polygon.
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    See Also
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    --------
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    polygon:
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        Generate coordinates of pixels inside a polygon.
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    Notes
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    -----
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    This function does not do any border checking. Parts of the polygon that
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    are outside the coordinate space defined by `image_shape` are not drawn.
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    Examples
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    --------
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    >>> import skimage as ski
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    >>> image_shape = (10, 10)
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    >>> polygon = np.array([[1, 1], [2, 7], [8, 4]])
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    >>> mask = ski.draw.polygon2mask(image_shape, polygon)
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    >>> mask.astype(int)
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    array([[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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           [0, 1, 0, 0, 0, 0, 0, 0, 0, 0],
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           [0, 0, 1, 1, 1, 1, 1, 1, 0, 0],
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           [0, 0, 1, 1, 1, 1, 1, 0, 0, 0],
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           [0, 0, 0, 1, 1, 1, 1, 0, 0, 0],
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           [0, 0, 0, 1, 1, 1, 0, 0, 0, 0],
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           [0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
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           [0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
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           [0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
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           [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]])
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    If vertices / points of the `polygon` are outside the coordinate space
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    defined by `image_shape`, only a part (or none at all) of the polygon is
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    drawn in the mask.
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    >>> offset = np.array([[2, -4]])
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    >>> ski.draw.polygon2mask(image_shape, polygon - offset).astype(int)
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    array([[0, 0, 0, 0, 0, 0, 1, 1, 1, 1],
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           [0, 0, 0, 0, 0, 0, 1, 1, 1, 1],
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           [0, 0, 0, 0, 0, 0, 0, 1, 1, 1],
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           [0, 0, 0, 0, 0, 0, 0, 1, 1, 1],
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           [0, 0, 0, 0, 0, 0, 0, 0, 1, 1],
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           [0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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           [0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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           [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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           [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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           [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]])
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    """
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    polygon = np.asarray(polygon)
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    vertex_row_coords, vertex_col_coords = polygon.T
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    fill_row_coords, fill_col_coords = draw.polygon(
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        vertex_row_coords, vertex_col_coords, image_shape
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    )
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    mask = np.zeros(image_shape, dtype=bool)
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    mask[fill_row_coords, fill_col_coords] = True
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    return mask
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