dist.py 文件源码

def SAM(s1, s2):
    """
    Computes the spectral angle mapper between two vectors (in radians).

    Parameters:
        s1: `numpy array`
            The first vector.

        s2: `numpy array`
            The second vector.

    Returns: `float`
            The angle between vectors s1 and s2 in radians.
    """
    try:
        s1_norm = math.sqrt(np.dot(s1, s1))
        s2_norm = math.sqrt(np.dot(s2, s2))
        sum_s1_s2 = np.dot(s1, s2)
        angle = math.acos(sum_s1_s2 / (s1_norm * s2_norm))
    except ValueError:
        # python math don't like when acos is called with
        # a value very near to 1
        return 0.0
    return angle