如何使用matpltlib.pyplot绘制按月和年分组的条形图？

import matplotlib.pyplot as plt
import numpy as np

months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
years = [2018, 2019, 2020, 2021]
data = np.random.randint(0, 100, size=(len(years), len(months)))

fig, ax = plt.subplots(figsize=(10, 6))

bar_width = 0.2
for i, year in enumerate(years):
    x = np.arange(len(months))
    y = data[i]
    ax.bar(x + i * bar_width, y, bar_width, label=str(year))

ax.set_xlabel('Month')
ax.set_ylabel('Value')
ax.set_title('Monthly Value by Year')
ax.set_xticks(x + bar_width * (len(years) - 1) / 2)
ax.set_xticklabels(months)
ax.legend()

plt.show()