具有两条线的单个图例项

import matplotlib.pyplot as plt

# 创建一些示例数据
x = [1, 2, 3, 4, 5]
y1 = [1, 4, 9, 16, 25]
y2 = [1, 2, 3, 4, 5]

# 创建图形和轴对象
fig, ax = plt.subplots()

# 绘制两条线
line1, = ax.plot(x, y1, label='Line 1')
line2, = ax.plot(x, y2, label='Line 2')

# 将两条线合并到一个图例项中
lines = [line1, line2]
labels = ['Combined Line']
ax.legend(lines, labels, loc='upper left')

# 显示图形
plt.show()