小编mrb*_*rti的帖子

我想用给定组的最后一个有效值填充数据帧NaN.例如:

import pandas as pd
import random as randy
import numpy as np

df_size = int(1e1)                
df = pd.DataFrame({'category': randy.sample(np.repeat(['Strawberry','Apple',],df_size),df_size), 'values': randy.sample(np.repeat([np.NaN,0,1],df_size),df_size)}, index=randy.sample(np.arange(0,10),df_size)).sort_index(by=['category'], ascending=[True])

提供:

     category   value
7       Apple     NaN
6       Apple       1
4       Apple       0
5       Apple     NaN
1       Apple     NaN
0  Strawberry       1
8  Strawberry     NaN
2  Strawberry       0
3  Strawberry       0
9  Strawberry     NaN

我想要计算的列如下所示:

     category   value  last_value
7       Apple     NaN         NaN
6       Apple       1         NaN
4       Apple       0           1
5       Apple     NaN           0
1       Apple     NaN …