(a, b, c)
return angle
Measure angle between a-b, b-c. In radians.
    Helper for gdf_to_nx.
Measure angle between a-b, b-c. In radians.
    Helper for gdf_to_nx.
Measure angle between a - b b - c . In radians . Helper for gdf_to_nx .
def _angle(a, b, c):
    """
    Measure angle between a-b, b-c. In radians.
    Helper for gdf_to_nx.
    """
    ba = [aa - bb for aa, bb in zip(a, b)]
    bc = [cc - bb for cc, bb in zip(c, b)]
    nba = math.sqrt(sum((x ** 2.0 for x in ba)))
    ba = [x / nba for x in ba]
    nbc = math.sqrt(sum((x ** 2.0 for x in bc)))
    bc = [x / nbc for x in bc]
    scal = sum((aa * bb for aa, bb in zip(ba, bc)))
    angle = math.acos(round(scal, 10))
    return angle
def _angle ( a , b , c ) : ba = [ aa - bb for aa , bb in zip ( a , b ) ] bc = [ cc - bb for cc , bb in zip ( c , b ) ] nba = math . sqrt ( sum ( ( x ** 2.0 for x in ba ) ) ) ba = [ x / nba for x in ba ] nbc = math . sqrt ( sum ( ( x ** 2.0 for x in bc ) ) ) bc = [ x / nbc for x in bc ] scal = sum ( ( aa * bb for aa , bb in zip ( ba , bc ) ) ) angle = math . acos ( round ( scal , 10 ) ) return angle