Are all rows per group equal to …?

I need to make sure all rows per id are equal to red to distinguish id 1 from id 2:

import pandas as pd

data = {"id":[1,1,1,2,2,2],
        "status":["red","red","red","green","red","red"]}
df= pd.DataFrame(data)
   # id status
   # 1    red
   # 1    red
   # 1    red
   # 2  green
   # 2    red
   # 2    red


df[df.loc[df["status"]=="red"].groupby("id").size() / df.groupby("id").status.size()==1]
#IndexingError: Unalignable boolean Series provided as indexer (index of the boolean Series and of the indexed object do not match).

#It is enough if the output is a series/list/array of the ids where all rows are red.

>Solution :

To get all the IDs with only "red", you can use groupby.transform:

out = df[df['status'].eq('red').groupby(df['id']).transform('all')]

Variant:

keep = df['status'].eq('red').groupby(df['id']).all()

out = df[df['id'].isin(keep[keep].index)]

Output:

   id status
0   1    red
1   1    red
2   1    red

Intermediates:

df['is_red'] = df['status'].eq('red')
df['all_red'] = df.groupby('id')['is_red'].transform('all')

   id status  is_red  all_red
0   1    red    True     True
1   1    red    True     True
2   1    red    True     True
3   2  green   False    False
4   2    red    True    False
5   2    red    True    False