python - Pandas dataframe 按一些值填充

Question

我有这个数据

import numpy as np
import pandas as pd
group = {'gender': ['male', 'female', 'female', 'male', 'female', 'male', 'male'],
        'height': [175, 168, np.nan, 170, 167, np.nan, 190],
        }
labels = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
df = pd.DataFrame(group, index=labels)
df2 = df.groupby('gender')['height'].mean()

我想用 df2 的平均值填充 nan

Answer 1

您可以使用 groupby + transform 和 mean。然后用结果系列fillna。

means = df.groupby('gender')['height'].transform('mean')
df['height'] = df['height'].fillna(means)

print(df)

   gender      height
a    male  175.000000
b  female  168.000000
c  female  167.500000
d    male  170.000000
e  female  167.000000
f    male  178.333333
g    male  190.000000