在 matplotlib 中旋转第二个 y 轴刻度标签答案

【问题标题】：Rotating 2nd y-axis tick labels in matplotlib在 matplotlib 中旋转第二个 y 轴刻度标签
【发布时间】：2020-03-04 22:21:52
【问题描述】：

我需要在下图中旋转第二个 y 轴刻度标签并为该轴添加一个标签

import matplotlib.pyplot as plt
import matplotlib.lines as mlines
import matplotlib.transforms as mtransforms

fig, ax1 = plt.subplots(constrained_layout=True)
x = [61,62,62,59,62,59,62,63,61,60,103,104,109,105,109,105,109,111,110,107]
y = [62,62,62,62,60,60,62,62,62,63,106,107,106,106,105,105,105,106,107,108]
ax1.plot(x,y,'b.')
x2 = [2.2,3.4,4.3,5.1,5.5,5.7]
y2 = [2.3,2.8,3.2,3.9,4.5,5.9]
ax2 = ax1.twinx().twiny()
ax2.tick_params(axis="y",labelrotation=90,direction='out',length=6, width=2, colors='r',grid_color='r', grid_alpha=0.5) #called tick_params before the plot and didn't work
ax2.plot(x2,y2,'r.')
ax2.set_xlim(0,10)
ax2.set_ylim(0,10)
ax2.set_yticklabels(['Label1', 'Label2', 'Label3'], rotation=90) #y ticklabels is not rotating
ax2.set_xlabel('abc', rotation=0, fontsize=20, labelpad=20)
ax2.set_ylabel('abc', rotation=0, fontsize=20, labelpad=20)   #y label is not wroking

plt.yticks(rotation=90)

line = mlines.Line2D([0, 1], [0, 1], color='red')
transform = ax2.transAxes
line.set_transform(transform)
ax2.add_line(line)
plt.show()

这段代码生成了下图

问题是 ax2.set_yticklabels 和 ax2.set_ylabel 不起作用。

我想为第二个 y 轴添加一个标签并旋转该轴的刻度标签。另外，如何控制这些轴上刻度线的位置，我希望它与第一个 y 轴和第一个 x 轴的刻度线位置相同。所以Label1会上移，0会右移

谢谢

【问题讨论】：

标签： python matplotlib

【解决方案1】：

当您实例化ax2 = ax1.twinx().twiny() 时，您无法再修改 y 轴。相反，创建两个轴并进行相应修改。修改后的代码，结果如下。

import matplotlib.pyplot as plt
import matplotlib.lines as mlines
import matplotlib.transforms as mtransforms

fig, ax1 = plt.subplots(constrained_layout=True)
x = [61,62,62,59,62,59,62,63,61,60,103,104,109,105,109,105,109,111,110,107]
y = [62,62,62,62,60,60,62,62,62,63,106,107,106,106,105,105,105,106,107,108]
ax1.plot(x,y,'b.')
x2 = [2.2,3.4,4.3,5.1,5.5,5.7]
y2 = [2.3,2.8,3.2,3.9,4.5,5.9]
ax2 = ax1.twinx()  # ax2 handles y
ax3 = ax2.twiny()  # ax3 handles x
ax3.plot(x2,y2,'r.')
ax3.set_xlim(0,10)
ax2.set_ylim(0,10)
ax3.set_xlabel('abc', rotation=0, fontsize=20, labelpad=20)
ax2.set_ylabel('abc', rotation=0, fontsize=20, labelpad=20)   
ax2.tick_params(axis="y",labelrotation=90,direction='out',length=6, width=2, colors='r',grid_color='r', grid_alpha=0.5)
ax2.set_yticklabels(['Label1', 'Label2', 'Label3'], rotation=-90)     
plt.yticks(rotation=90)
line = mlines.Line2D([0, 1], [0, 1], color='red')
transform = ax2.transAxes
line.set_transform(transform)
ax2.add_line(line)
plt.show()

结果图包含所有 y 标签/刻度修改。

【讨论】：