Populate next row event in current row based on the event in Pandas dataframe

BrkPressState	VehSpdGS
1	2
1	3
1	2
1	4
0	12
0	13
0	11
1	3
0	15
0	14
0	15
1	12
1	13
0	14

For the above table i am trying to populate the next row value in previous last event, Like the below table

I tried with Shift – 1 but its populating only for the current row , Sample code which i tried.

d['result']=d.loc[d['BrkPressState'] != d['BrkPressState'].shift(-1), 'VehSpdGS'] 

Expected output:

Answer

Let us do diff to compare the previous and current row in BrkPressState column in order to identify boundaries, then mask and shift the values in VehSpdGS column

m = df['BrkPressState'].diff().ne(0)
df['Results'] = df['VehSpdGS'].mask(~m).shift(-1)

---

    BrkPressState  VehSpdGS  Results
0               1         2      NaN
1               1         3      NaN
2               1         2      NaN
3               1         4     12.0
4               0        12      NaN
5               0        13      NaN
6               0        11      3.0
7               1         3     15.0
8               0        15      NaN
9               0        14      NaN
10              0        15     12.0
11              1        12      NaN
12              1        13     14.0
13              0        14      NaN