在图例中将两个matplotlib标记合并为一个

import matplotlib.pyplot as plt

# 创建一个图形对象
fig, ax = plt.subplots()

# 创建两个示例数据
x = [1, 2, 3, 4]
y1 = [1, 2, 3, 4]
y2 = [4, 3, 2, 1]

# 绘制两个标记
line1, = ax.plot(x, y1, marker='o', label='数据1')
line2, = ax.plot(x, y2, marker='s', label='数据2')

# 定义自定义图例处理函数
def merge_legend_labels(handler, orig_labels, fontsize):
    merged_label = '数据1+数据2'
    return merged_label

# 设置图例处理函数
ax.legend(handler_map={line1: merge_legend_labels})

# 显示图形
plt.show()