How to plot smooth curve through the true data points

Question

I have tried a bunch of spline examples already posted for plotting smooth curves in python but those smoothed curves don't always cross through the true points. So far, I tried using make_interp_spline, interp1dand also BSpline.

Is there any way (any spline option) I can plot a smooth curve that must include/cross through true data points?

Answer 1

Here is a simple example with interp1d:

import numpy as np
import matplotlib.pyplot as plt
from scipy.interpolate import interp1d

x = np.arange(5)
y = np.random.random(5)
fun = interp1d(x=x, y=y, kind=2)
x2 = np.linspace(start=0, stop=4, num=1000)
y2 = fun(x2)

plt.plot(x2, y2, color='b')
plt.plot(x, y, ls='', marker='o', color='r')

plt.show()

You can easily verify that this interpolation includes the true data points:

assert np.allclose(fun(x), y)