Matplotlib向熊猫色图添加图例

Question

我有一个熊猫数据框df，它有一列，我可以用这种方式为matplotlib创建一个颜色代码列

df['color-code'] = np.where(df['Community School?']=='Yes', 'blue', 'red')

我还创建了一个单独的数据框，以使用没有空值的绘图

sc_income = df[~df['Economic Need Index'].isnull() & ~df['School Income Estimate'].isnull()]

然后我用

#make plot bigger
plt.rcParams['figure.figsize'] = (40,20)

#plot Economic Need Index vs School Income Estimate
scatter(sc_income['Economic Need Index'], sc_income['School Income Estimate'], c=sc_income['color-code'])
plt.xlabel('Economic Need')
plt.ylabel('School Income $')

plt.title('Economic Need vs. School Income')
plt.legend()
plt.show()

最终情节看起来像这样

需要的图例应指定蓝色表示社区学校，红色表示不是社区学校。

Answer 1

您尝试按组着色点。有很多方法可以做到这一点。使用matplotlib：

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

# generate data
n_obs = 100
df = pd.DataFrame({'Community School?': np.random.choice(['Yes', 'No'], size=n_obs),
                   'Economic Need Index': np.random.uniform(size=n_obs),
                   'School Income Estimate': np.random.normal(loc=n_obs, size=n_obs)})

# your data pre-processing steps
df['color-code'] = np.where(df['Community School?']=='Yes', 'blue', 'red')
sc_income = df[~df['Economic Need Index'].isnull() & ~df['School Income Estimate'].isnull()]

# plot Economic Need Index vs School Income Estimate by group
groups = sc_income.groupby('Community School?')

fig, ax = plt.subplots(1, figsize=(40,20))

for label, group in groups:
    ax.scatter(group['Economic Need Index'], group['School Income Estimate'], 
               c=group['color-code'], label=label)

ax.set(xlabel='Economic Need', ylabel='School Income $', 
       title='Economic Need vs. School Income')
ax.legend(title='Community School?')
plt.show()

或者使用seaborn和pairplot例如：

g = sns.pairplot(x_vars='Economic Need Index', y_vars='School Income Estimate', data=sc_income, 
                 hue="Community School?", size=5)
g.set(xlabel='Economic Need', ylabel='School Income $', title='Economic Need vs. School Income')