plt.plot(x, noisy_data, label='noisy data')
plt.plot(x, splev(x, f), label='fitted')
plt.plot(x, splev(x, f, der=1) / 10, label='1st derivative')
plt.hlines(0, 0, 2)
plt.legend(loc=0)
plt.show()
Gradient in noisy data, python