根据另一列 Pandas，如果它们不为空，则用它们的邻居填充空单元格

Question

Good afternoon,

What is the simplest way to replace empty values to another value in one column if the text in the another column is equal?

For example, we have the dataframe:

Name	Life	Score
Joe	789	45
Joe	563	13
Nick		24
Nick	45	155
Alice	188	34
Alice		43
Kate		43543
Kate		232

And the result should be:

Name	Life	Score
Joe	789	45
Joe	563	13
Nick	45	24
Nick	45	155
Alice	188	34
Alice	188	43
Kate		43543
Kate		232

Thanks for all help!

Answer 1

You can do it like this:

import numpy as np
import pandas as pd

df = pd.DataFrame({
    'Name': ['Joe', 'Joe', 'Nick', 'Nick', 'Alice', 'Alice', 'Kate', 'Kate'],
    'Life': [789.0, np.nan, np.nan, 45.0, 188.0, np.nan, np.nan, np.nan],
    'Score': [45, 13, 24, 155, 34, 43, 43543, 232]
})
print(df)

# output:
#     Name   Life  Score
# 0    Joe  789.0     45
# 1    Joe    NaN     13
# 2   Nick    NaN     24
# 3   Nick   45.0    155
# 4  Alice  188.0     34
# 5  Alice    NaN     43
# 6   Kate    NaN  43543
# 7   Kate    NaN    232


df['Life'] = df.groupby('Name')['Life'].transform('first')
print(df)

# output:
#     Name   Life  Score
# 0    Joe  789.0     45
# 1    Joe  789.0     13
# 2   Nick   45.0     24
# 3   Nick   45.0    155
# 4  Alice  188.0     34
# 5  Alice  188.0     43
# 6   Kate    NaN  43543
# 7   Kate    NaN    232