scipy.interpolate not working code example

Example 1: smooth interpolation python

>>> from scipy.interpolate import UnivariateSpline
>>> x, y = np.array([1, 2, 3, 4]), np.array([1, np.nan, 3, 4])
>>> w = np.isnan(y)
>>> y[w] = 0.
>>> spl = UnivariateSpline(x, y, w=~w)

Example 2: smooth interpolation python

spl.set_smoothing_factor(0.5)
plt.plot(xs, spl(xs), 'b', lw=3)
plt.show()