如何像Plotly一样在Matplotlib中注释datetime格式？

Question

如何像Plotly一样在Matplotlib中添加注释文本示例1st Lockdown, 2nd Lockdown

Answer 1

下面是一个使用^{}的示例，另一个答案是：

import matplotlib.pyplot as plt
import pandas as pd

dr = pd.date_range('02-01-2020', '07-01-2020', freq='1D')

y = pd.Series(range(len(dr))) ** 2

fig, ax = plt.subplots()
ax.plot(dr, y)

ax.annotate('1st Lockdown',
            xy=(dr[50], y[50]), #annotate the 50th data point; you could select this in a better way
            xycoords='data', #the xy we passed refers to the data
            xytext=(0, 100), #where we put the text relative to the xy
            textcoords='offset points', #what the xytext coordinates mean
            arrowprops=dict(arrowstyle="->"), #style of the arrow
            ha='center') #center the text horizontally

ax.annotate('2nd Lockdown',
            xy=(dr[100], y[100]), xycoords='data',
            xytext=(0, 100), textcoords='offset points',
            arrowprops=dict(arrowstyle="->"), ha='center')

有很多带有注解的选项，所以我会look for an example匹配您想要做的事情，并尝试遵循它

注释似乎是在matplotlib中实现这一点的“聪明”方式；您也可以只使用axvline和text，但您可能需要添加额外的格式以使事情看起来更好：

import matplotlib.pyplot as plt
import pandas as pd

dr = pd.date_range('02-01-2020', '07-01-2020', freq='1D')

y = pd.Series(range(len(dr))) ** 2

fig, ax = plt.subplots()
ax.plot(dr, y)

ax.axvline(dr[50], ymin=0, ymax=.7, color='gray')
ax.text(dr[50], .7, '1st Lockdown', transform=ax.get_xaxis_transform(), color='gray')

Answer 2

尝试使用

ax.annotate('1st Lockdown', ...)

见https://matplotlib.org/3.3.1/tutorials/text/annotations.html#plotting-guide-annotation