import pyquaternion

def getQfromR(R):
    return pyquaternion.Quaternion(matrix=R)

def quaternion_distance(r1, r2):
    r1 = r1.reshape((3, 3))
    r2 = r2.reshape((3, 3))
    q1 = getQfromR(r1)
    q2 = getQfromR(r2)
    dist =  q1 * q2.inverse
    return dist.degrees