Matplotlib plotting notes

使用Python中的Matplotlib绘图,There are some functions that are not fully remembered,Every time you have to go online to find the corresponding code usage,Take this article as a note,记录常用、Uncommon usage.
官方文档地址：https://matplotlib.org/stable/api/axes_api.html

坐标轴

Axis label density

MultipleLocator(1)表示间距为1.

from matplotlib import ticker
ax.xaxis.set_major_locator(ticker.MultipleLocator(1))
ax.yaxis.set_major_locator(ticker.MultipleLocator(1))

不显示坐标轴

All borders will be hidden at once.

plt.axis('off')

The scale of the horizontal and vertical axes

Let the ratio of the horizontal and vertical axes be 1:1.

plt.gca().set_aspect(1)

坐标轴范围

It is used in the normal single-image situationplt.xlim(xmin,xmax).Use in multi-image situationsax.set(xlim=(xmin, xmax),ylim=(ymin,ymax)）.

# Generally used for single image
plt.xlim(xmin, xmax)
plt.ylim(ymin, ymax)
# Multi-map case
ax.set(xlim=(xmin, xmax), ylim=(ymin, ymax))
# or single image use
plt.gca().set(xlim=(xmin, xmax), ylim=(ymin, ymax))

子图

生成子图

生成子图,plt.subplots(行数,列数),返回的axesis a two-dimensional index structure.

fig, axes = plt.subplots(nrows=2, ncols=2)

Flatten a two-dimensional index structure into a one-dimensional index structure,axes.flatten()

for i, ax in enumerate(axes.flatten()):
	ax.plot(x, y)

子图标题

使用ax.set_title(‘title’)The name of the marker subgraph,此时,The title is usually at the top of the figure.

ax.set_title('title')

To make the title at the bottom of the figure,使用y=-0.2,Defines the position of the title.

ax.set_title('title', y=-0.2)

fontsize=15,调整字体大小.

ax.set_title('title', y=-0.2, fontsize=15)

子图间距

通过plt.subplots_adjust进行调整,参数里面的top, left, right, rightIt corresponds to the bottom left corner of the image as the origin,The position ratio of the top, bottom, left, and right corners,取值为0-1.wspace和hspaceControls the vertical and horizontal spacing between subplots.

plt.subplots_adjust(left, bottom, right, top, wspace, hspace)

Sets the display range of the subplot axes

如果使用plt.xlim(xmin, xmax)的方式,在迭代过程中,This range limit only applies to the last subgraph,The correct way is to use for each subplotax.set(xlim=(xmin,xmax))的方法.
参见：https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.axis.html

fig, axes = plt.subplots(2, 3)
for i, ax in enumerate(axes.flatten()):
	ax.set(xlim=(xmin, xmax), ylim=(ymin,ymax))

绘制

绘制箭头

由xytextthe coordinates point toxy的坐标.

    plt.gca().annotate("", xy=(0, 2.5), xytext=(0, -1.2),
            arrowprops=dict(arrowstyle="->"))

Write text on the image

使用$$之后,与LaTeX的使用方法一样.

plt.text(x=1, y=2, s=r'$\hat{\beta}$')