I have a DataFrame that contains the following columns (along with others). I am trying to figure out how to remove all rows where: For each group number in ID_Dets if there exists more than 1 unique number in ID_Dets_2 then drop all rows.

I have bolded the rows that I would want removed. Thx!

CodePudding user response：

You can count the number of unique values per group and set a threshold to have 1 unique value:

df[df.groupby('ID_Dets')['ID_Dets_2'].transform('nunique').eq(1)]

or:

df.groupby('ID_Dets').filter(lambda g: len(g['ID_Dets_2'].unique())<=1)

output:

   Index Other Columns  ID_Dets  ID_Dets_2
0     11           aga        4          5
1     13            af        2          3
2     14            da        3          4
3     15           aga        3          4
8      4            ga        1          2
9      5           aah        1          2

CodePudding user response：

I think the answer by mozway is way slicker than mine, but I was working on it so might as well post it...

You can generate a list of ids to remove and then filter on that list.

ids_to_remove = []
for v in df['ID_Dets'].unique():
    if df[df['ID_Dets'] == v]["ID_Dets_2"].nunique() > 1: ids_to_remove.append(a)
df = df[~df['ID_Dets'].isin(ids_to_remove)]