[SOLVED] Get groups where values go from 0 to 1

Issue

I want to get all the users from a dataframe where a specific column goes from 1 to 0.

For example, with the following dataframe I want to keep only user 1 and 2 as their values go from 1 to 0.

Relevant rows

• Row 6 to 7 for user 1
• Row 9 to 10 for user 2

    user  value
0      0      0
1      0      0
2      0      1
3      0      1
4      1      0
5      1      1
6      1      1
7      1      0
8      2      1
9      2      1
10     2      0
11     2      0

Desired Result

    user  value
4      1      0
5      1      1
6      1      1
7      1      0
8      2      1
9      2      1
10     2      0
11     2      0

I have tried window functions and conditions but for some reason I cannot get the desired result.

Solution

Let us try cummax

df.loc[df.user.isin(df.loc[df.value != df.groupby('user')['value'].cummax(),'user'])]
Out[769]: 
    user  value
4      1      0
5      1      1
6      1      1
7      1      0
8      2      1
9      2      1
10     2      0
11     2      0

Answered By – BENY

Answer Checked By – David Goodson (BugsFixing Volunteer)