Fillna，模式逐列

Question

我得到了一些像这样的东西: x: Users y:评级

这显示了用户1对具有4.0的电影1进行评级，用户1不对电影2进行评级，用户1对具有1.0的电影3进行评级，依此类推

       rating
movieId 1      2      3      4     5   .....
userID
1      4.0    NaN     1.0   4.1    NaN
2      NaN      2     5.1   NaN    NaN
3      3.0    2.0     NaN   NaN    NaN
4      5.0    NaN     2.8   NaN    NaN

如何使用电影模式填充NaN值

示例movieId 1的评级为4.0，NaN，3.0，5.0.....然后用4.0填充NaNs (模式)我试着用fill NaNs

rating.apply(lambda x: x.fillna(x.mode().item()))

Answer 1

试一试

rating.apply(lambda x: x.fillna(x.mode()), axis=0)

指定axis=0

或者，

import numpy as np
import pandas as pd

def fillna_mode(df, cols_to_fill):
    for col in cols_to_fill:
        df[col].fillna(df[col].mode()[0], inplace=True)

sample = {1: [4.0, np.nan,1.0, 4.1, np.nan],
          2: [np.nan, 2, 5.1, np.nan, np.nan]}

rating = pd.DataFrame(sample)

print(rating)

      1 2
0   4.0 NaN
1   NaN 2.0
2   1.0 5.1
3   4.1 NaN
4   NaN NaN

fillna_mode(rating, [1, 2])

输出

    1   2
0   4.0 2.0
1   1.0 2.0
2   1.0 5.1
3   4.1 2.0
4   1.0 2.0