Python Pandas same value col A having col B value different

Question

A Pandas solution to get result Dataframe when values B are not same for same A value

IN:

colA  colB
a     1 <--
b     2
a     1 <--
a     0 <-- different

OUT:

colA  colB
a     1 <--
a     1 <--
a     0 <-- different

SOLUTION:

Pandas Groupby Select Groups that Have More Than One Unique Values in a Column

out = df.groupby(['a']).filter(lambda x: x['b'].nunique() > 1)

@mozway comment works too

out = df[df.groupby('colA')['colB'].transform('nunique').gt(1)]

Answer 1

result = df[df.duplicated(subset='colA', keep=False) | ~df.duplicated(subset='colA', keep=False)]

Then if you don't want duplicates:

result.drop_duplicates(inplace=True)