#! /usr/bin/python3

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle

fig, axs = plt.subplots(nrows=3, figsize=(10, 5))
[ax.grid(True) for ax in axs]

dx_values = [0.5, 0.2, 0.1]
for idx, dx in enumerate(dx_values):
    for x in np.arange(0, 2*np.pi, dx):
        axs[idx].add_patch(Rectangle(xy=(x, 0), width=dx, height=np.sin(x), color=(1, 0, 0, 0.2)))

    x = np.arange(0, 2*np.pi, 0.01)
    y = np.sin(x)
    axs[idx].plot(x, y)

plt.show()