添加覆盖 twinx 轴线条的图例

我有这个Python代码。

1. 它与轴成对ax并在两个轴上绘制一些函数
2. 我将图例绘制在ax1

问题是图例没有覆盖曲线ax2

有可能自动定位传说中的ax通过覆盖线ax2.

请注意，在fig.legend选项loc="best"不可用。 我需要在绘图区域内自动定位。

Tnx

import matplotlib.pyplot as plt
import numpy as np

# Set the x values for the sine and cosine functions
x = np.linspace(0, 2*np.pi, 100)

# Create the figure and an axis
fig, ax = plt.subplots()
ax2 = ax.twinx()

# Plot the sine and cosine functions on the axis
ax.plot(x, np.sin(x), label='Sine')
ax.plot(x, np.cos(x), label='Cosine')

ax2.plot(x, np.cos(x+1), label='Cosine 2', color="red")
ax2.plot(x, x, label='Cosine 2', color="green")

# Add a title and labels to the axis
ax.set_title('Sine and Cosine Functions')
ax.set_xlabel('X')
ax.set_ylabel('Y')

# Get the line legends from the axis
lines, labels = ax.get_legend_handles_labels()
lines2, labels2 = ax2.get_legend_handles_labels()

# Add a legend to the figure
ax.legend(lines + lines2, labels + labels2, framealpha=1.0)
ax.get_legend().set_zorder(10)

# Display the plot
plt.show()

下面是代码的输出：

参考：

https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.legend.html https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.legend.html https://matplotlib.org/stable/gallery/misc/zorder_demo.html https://matplotlib.org/stable/gallery/misc/zorder_demo.html

The zorder of a legend默认是最高的，所以如果你想要的话，不需要修改它legend在一切之上。

选项1：

您可以通过以下方式完成此任务Figure对象而不是Axes对象与plt.legend(lines + lines2, labels + labels2, framealpha=1.0, loc='lower left').

选项2：

或者您可以将图例设置为ax2代替ax with ax2.legend(lines + lines2, labels + labels2, framealpha=1.0, loc='lower left')。这将返回与选项 1 相同的结果。

import matplotlib.pyplot as plt
import numpy as np

# Set the x values for the sine and cosine functions
x = np.linspace(0, 2 * np.pi, 100)

# Create the figure and an axis
fig, ax = plt.subplots()
ax2 = ax.twinx()

# Plot the sine and cosine functions on the axis
ax.plot(x, np.sin(x), label='Sine')
ax.plot(x, np.cos(x), label='Cosine')

ax2.plot(x, np.cos(x + 1), label='Cosine 2', color="red")
ax2.plot(x, x, label='Cosine 2', color="green")

# Add a title and labels to the axis
ax.set_title('Sine and Cosine Functions')
ax.set_xlabel('X')
ax.set_ylabel('Y')

# Get the line legends from the axis
lines, labels = ax.get_legend_handles_labels()
lines2, labels2 = ax2.get_legend_handles_labels()

# Add a legend to the figure
plt.legend(lines + lines2, labels + labels2, framealpha=1.0, loc='lower left')

# Display the plot
plt.show()

结果 （loc='lower left' and loc='lower center'):

Updated:

参考：https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.twinx.html https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.twinx.html

对于我之前的答案中的选项 2，我将第 36 行编辑为ax2.legend(lines + lines2, labels + labels2, framealpha=1.0, loc='lower right')和第 43 行到ax22.legend(lines1 + lines22, labels1 + labels22, framealpha=1.0, loc='lower left')在您新提供的代码中。

如果您有多个子图，请使用Axes对象更加灵活。

现在可以正常工作了：