image_signature.py 文件源码

def normalized_distance(_a, _b):
    """Compute normalized distance between two points.

    Computes 1 - a * b / ( ||a|| * ||b||)

    Args:
        _a (numpy.ndarray): array of size m
        _b (numpy.ndarray): array of size m

    Returns:
        normalized distance between signatures (float)

    Examples:
        >>> a = gis.generate_signature('https://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Mona_Lisa,_by_Leonardo_da_Vinci,_from_C2RMF_retouched.jpg/687px-Mona_Lisa,_by_Leonardo_da_Vinci,_from_C2RMF_retouched.jpg')
        >>> b = gis.generate_signature('https://pixabay.com/static/uploads/photo/2012/11/28/08/56/mona-lisa-67506_960_720.jpg')
        >>> gis.normalized_distance(a, b)
        0.0332806110382

    """

    # return (1.0 - np.dot(_a, _b) / (np.linalg.norm(_a) * np.linalg.norm(_b)))
    return np.dot(_a, _b) / (np.linalg.norm(_a) * np.linalg.norm(_b))