添加圖例 seaborn 條形圖

Question

這是我的代碼：

import numpy as np
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt

array = np.array([[1,5,9],[3,5,7]])

df = pd.DataFrame(data=array, index=['Positive', 'Negative'])

f, ax = plt.subplots(figsize=(8, 6))

current_palette = sns.color_palette('colorblind')

ax_pos = sns.barplot(x = np.arange(0,3,1), y = df.loc['Positive'].to_numpy(), color = current_palette[2], alpha = 0.66)
ax_neg = sns.barplot(x = np.arange(0,3,1), y = df.loc['Negative'].to_numpy(), color = current_palette[4], alpha = 0.66)

plt.xticks(np.arange(0,3,1), fontsize = 20)
plt.yticks(np.arange(0,10,1), fontsize = 20)

plt.legend((ax_pos[0], ax_neg[0]), ('Positive', 'Negative'))

plt.tight_layout()

不幸的是，我有這個錯誤：

類型錯誤：'AxesSubplot' object 不支持索引

我想知道為什么用 seaborn 不能調用這樣的圖例 (plt.legend(ax[0]...) 而用 matplotlib 是不可能的。最后，我只想要左上角的圖例。

Answer 1

我發現 barplot 有“標簽”function：

import numpy as np
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt

array = np.array([[1,5,9],[3,5,7]])

df = pd.DataFrame(data=array, index=['Positive', 'Negative'])

f, ax = plt.subplots(figsize=(8, 6))

current_palette = sns.color_palette('colorblind')

sns.barplot(x = np.arange(0,3,1), y = df.loc['Positive'].to_numpy(), color = current_palette[2], alpha = 0.66, label = "Positive")
sns.barplot(x = np.arange(0,3,1), y = df.loc['Negative'].to_numpy(), color = current_palette[4], alpha = 0.66, label = "Negative")

plt.xticks(np.arange(0,3,1), fontsize = 20)
plt.yticks(np.arange(0,10,1), fontsize = 20)

plt.legend(frameon = False)

plt.tight_layout()