How to merge two existing Matplotlib plots into one plot?

To merge two existing matplotlib plots into one plot, we can take the following steps −

Set the figure size and adjust the padding between and around the subplots.
Create x, y1 and y2 data points using numpy.
Plot (x, y1) and (x, y2) points using plot() method.
Get the xy data points of the current axes.
Use argsort() to return the indices that would sort an array.
Append x and y data points of each plot.
Plot X and Y data points at the 2nd index subplot.
To display the figure, use show() method.

Example

import numpy as np
import matplotlib.pyplot as plt

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

x = np.linspace(-10, 10, 100)
y1 = np.sin(x)
y2 = np.cos(x)

plt.subplot(211)
plt.plot(x, y1, color='red', lw=5)
plt.plot(x, y2, color='orange', lw=7)

X, Y = [], []

for lines in plt.gca().get_lines():
   for x, y in lines.get_xydata():
      X.append(x)
      Y.append(y)

idx = np.argsort(X)
X = np.array(X)[idx]
Y = np.array(Y)[idx]

plt.subplot(212)

plt.plot(X, Y, color='green', lw=0.75)

plt.show()