python - Counting unique values in a pandas grouped object -

i have table in pandas/python , doing following:

grouped_data = df_comments_cols['article_id'].groupby(df_comments_cols['user_id'])

now count number of articles per user following:

ct_grouped_data = grouped_data.count()

the above counts number of article ids per user. however, there multiple of same article ids per user (in sense user has interacted article more once) , wish count unique article ids per user - there quick way this?

thanks in advance.

i think might looking nunique, can call on groupby objects so:

in [63]: df = dataframe({'a': randn(1000, 1)})  in [64]: df['user_id'] = randint(100, 1000, size=len(df))  in [65]: df['article_id'] = randint(100, size=len(df))  in [66]: gb = df.article_id.groupby(df.user_id)  in [67]: gb.nunique() out[67]: user_id 100        2 101        1 102        1 104        2 105        1 106        2 107        1 110        1 111        4 112        2 113        1 114        2 115        1 116        1 118        1 ... 976        3 980        1 982        1 983        1 986        1 987        1 988        1 989        2 990        1 993        1 994        2 996        1 997        1 998        1 999        1 length: 617, dtype: int64