我想在 pyplot 中做类似以下的事情，我也可以在其中标记条形图和组。我能够标记条形，但不知道如何标记组。谢谢！
默认的Seaborn 条形图会创造一个传说来显示岁月：
import numpy as np
import pandas as pd
import seaborn as sns
labels = ['apples', 'bananas', 'coconuts', 'dates', 'elderberries', 'figs', 'grapes']
years = [2017, 2018, 2019]
df = pd.DataFrame({'Fruit': np.tile(labels, len(years)),
'Year': np.tile(years, len(labels)),
'Amount': np.random.uniform(1.5, 5, len(labels)*len(years))})
ax = sns.barplot(x='Fruit', y='Amount', hue='Year', data=df)
Placing text()用一个BlendedTransform可以将新标签放置在所需位置。clip_on=False需要在主轴区域之外绘制。可以通过添加垂直线axvline（这些使用BlendedTransform默认情况下）。新年标签可以放置在每个栏的位置。图例和默认的 xlabel 可以删除。
from matplotlib import pyplot as plt
from matplotlib import transforms
import numpy as np
import pandas as pd
import seaborn as sns
labels = ['apples', 'bananas', 'coconuts', 'dates', 'elderberries', 'figs', 'grapes']
years = [2017, 2018, 2019]
df = pd.DataFrame({'Fruit': np.tile(labels, len(years)),
'Year': np.tile(years, len(labels)),
'Amount': np.random.uniform(1.5, 5, len(labels)*len(years))})
fig, ax = plt.subplots(figsize=(12, 4))
ax = sns.barplot(x='Fruit', y='Amount', hue='Year', palette='Reds', data=df, ax=ax)
year_pos = np.sort( [p.get_x() + p.get_width()/2 for p in ax.patches])
ax.set_xticks(year_pos)
ax.set_xticklabels(np.tile(years, len(labels)), rotation=30)
ax.get_legend().remove()
ax.set_xlabel('') # remove default xlabel
fruit_pos = year_pos.reshape(-1, len(years)).mean(axis=1)
trans = transforms.blended_transform_factory(ax.transData, ax.transAxes)
for pos, label in zip(fruit_pos, labels):
ax.text(pos, -0.25, label, transform=trans, ha='center', va='bottom', color='steelblue', fontsize=14)
for pos in (fruit_pos[:-1] + fruit_pos[1:]) / 2:
ax.axvline(pos, 0, -0.25, color='steelblue', ls=':' , clip_on=False)
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
plt.tight_layout()
plt.show()
