a = np.array([[0.0, 0.0], [0.3, 0.0], [1.25, -0.1], [2.1, -0.9], [2.85, 
    -2.3], [3.8, -3.95], [5.0, -5.75], [6.4, -7.8], [8.05, -9.9], [9.9, 
    -11.6], [12.05, -12.85], [14.25, -13.7], [16.5, -13.8], [19.25, -13.35],
    [21.3, -12.2], [22.8, -10.5], [23.55, -8.15], [22.95, -6.1], [21.35, 
    -3.95], [19.1, -1.9]])
Curve curvature in numpy