有关使用matplotlib向分组条形图添加条形图标签的问题

import matplotlib.pyplot as plt
import numpy as np

categories = ['A', 'B', 'C', 'D', 'E']  # 分组的类别
group1 = [20, 34, 30, 35, 27]  # 第一组数据
group2 = [25, 32, 34, 20, 25]  # 第二组数据
group3 = [12, 28, 15, 32, 18]  # 第三组数据

bar_width = 0.2  # 条形图的宽度
index = np.arange(len(categories))  # x轴坐标位置

plt.bar(index, group1, bar_width, label='Group 1')
plt.bar(index + bar_width, group2, bar_width, label='Group 2')
plt.bar(index + 2*bar_width, group3, bar_width, label='Group 3')

plt.xlabel('Categories')
plt.ylabel('Values')
plt.title('Grouped Bar Chart')
plt.xticks(index + bar_width, categories)
plt.legend()

def add_labels(data):
    for i in range(len(data)):
        plt.text(i, data[i]+1, str(data[i]), ha='center')

add_labels(group1)
add_labels(group2)
add_labels(group3)

plt.tight_layout()
plt.show()