Question

figures, axes 和 ticks 的关系

这些对象的关系可以用下面的图来表示：

示例图像：

具体结构：

figure 对象

figure 对象是最外层的绘图单位，默认是以 1 开始编号（MATLAB 风格，Figure 1, Figure 2, ...），可以用 plt.figure() 产生一幅图像，除了默认参数外，可以指定的参数有：

• num - 编号
• figsize - 图像大小
• dpi - 分辨率
• facecolor - 背景色
• edgecolor - 边界颜色
• frameon - 边框

这些属性也可以通过 Figure 对象的 set_xxx 方法来改变。

subplot 和 axes 对象

subplot

subplot 主要是使用网格排列子图：

In [1]:

%pylab inline

subplot(2,1,1)
xticks([]), yticks([])
text(0.5,0.5, 'subplot(2,1,1)',ha='center',va='center',size=24,alpha=.5)

subplot(2,1,2)
xticks([]), yticks([])
text(0.5,0.5, 'subplot(2,1,2)',ha='center',va='center',size=24,alpha=.5)

show()

Populating the interactive namespace from numpy and matplotlib

https://www.wenjiangs.com/wp-content/uploads/2022/docimg20/NsFR5fQkDRRVzC2Q-UxVhH8.png alt="">

更高级的可以用 gridspec 来绘图：

In [2]:

import matplotlib.gridspec as gridspec

G = gridspec.GridSpec(3, 3)

axes_1 = subplot(G[0, :])
xticks([]), yticks([])
text(0.5,0.5, 'Axes 1',ha='center',va='center',size=24,alpha=.5)

axes_2 = subplot(G[1,:-1])
xticks([]), yticks([])
text(0.5,0.5, 'Axes 2',ha='center',va='center',size=24,alpha=.5)

axes_3 = subplot(G[1:, -1])
xticks([]), yticks([])
text(0.5,0.5, 'Axes 3',ha='center',va='center',size=24,alpha=.5)

axes_4 = subplot(G[-1,0])
xticks([]), yticks([])
text(0.5,0.5, 'Axes 4',ha='center',va='center',size=24,alpha=.5)

axes_5 = subplot(G[-1,-2])
xticks([]), yticks([])
text(0.5,0.5, 'Axes 5',ha='center',va='center',size=24,alpha=.5)

show()

https://www.wenjiangs.com/wp-content/uploads/2022/docimg20/ktbVQ75OzPpiwwQp-pPjblC.png alt="">

axes 对象

subplot 返回的是 Axes 对象，但是 Axes 对象相对于 subplot 返回的对象来说要更自由一点。Axes 对象可以放置在图像中的任意位置：

In [3]:

axes([0.1,0.1,.8,.8])
xticks([]), yticks([])
text(0.6,0.6, 'axes([0.1,0.1,.8,.8])',ha='center',va='center',size=20,alpha=.5)

axes([0.2,0.2,.3,.3])
xticks([]), yticks([])
text(0.5,0.5, 'axes([0.2,0.2,.3,.3])',ha='center',va='center',size=16,alpha=.5)

show()

https://www.wenjiangs.com/wp-content/uploads/2022/docimg20/2kcv1aNR6PbohkcD-pn6ELY.png alt="">

In [4]:

axes([0.1,0.1,.5,.5])
xticks([]), yticks([])
text(0.1,0.1, 'axes([0.1,0.1,.8,.8])',ha='left',va='center',size=16,alpha=.5)

axes([0.2,0.2,.5,.5])
xticks([]), yticks([])
text(0.1,0.1, 'axes([0.2,0.2,.5,.5])',ha='left',va='center',size=16,alpha=.5)

axes([0.3,0.3,.5,.5])
xticks([]), yticks([])
text(0.1,0.1, 'axes([0.3,0.3,.5,.5])',ha='left',va='center',size=16,alpha=.5)

axes([0.4,0.4,.5,.5])
xticks([]), yticks([])
text(0.1,0.1, 'axes([0.4,0.4,.5,.5])',ha='left',va='center',size=16,alpha=.5)

show()

https://www.wenjiangs.com/wp-content/uploads/2022/docimg20/zpUrI4rnqtd1WeoI-fybOsI.png alt="">

后面的 Axes 对象会覆盖前面的内容。

ticks 对象

ticks 用来注释轴的内容，我们可以通过控制它的属性来决定在哪里显示轴、轴的内容是什么等等。