pandas reset index after performing groupby and retain selective columns

Question

I want to take a pandas dataframe, do a count of unique elements by a column and retain 2 of the columns. But I get a multi-index dataframe after groupby which I am unable t

Answer 1

Try this instead:

1) Select only the relevant columns (['ID', 'Random_data'])

2) Don't pass a list to .agg - just 'nunique' - the list is what is causing the multi index behaviour.

df2 = df.groupby(['Ticker'])['ID', 'Random_data'].agg('nunique')
df2.reset_index()

  Ticker  ID  Random_data
0     AA   1            1
1     BB   2            2
2     CC   2            2
3     DD   1            1

Answer 2

Use SeriesGroupBy.nunique and filter columns in list after groupby:

df2 = df.groupby('Ticker')['Date_1','Count','ID'].nunique().reset_index()
print(df2)
  Ticker  Date_1  Count  ID
0     AA       1      1   1
1     BB       2      2   2
2     CC       2      2   2
3     DD       1      1   1