python - how to subset pandas dataframe on a condition -

i have pandas dataframe this:

 buyer_id meal_type     139       veg     140    nonveg     140       veg      36    nonveg      79       veg      79    nonveg      79    nonveg      72    nonveg      72    nonveg      65    nonveg      65       veg 

now want buyer_id has veg meal type,all buyer_id has veg , nonveg meal type , buyer_id has nonveg meal type.

so,

139 veg 140 veg , nonveg 36  nonveg 79  veg , nonveg 

and on. doing following in python buyer ids have veg, nonveg or both.

segments_data.buyer_id[segments_data['meal_type']=='veg' &       segments_data['meal_type']=='nonveg'] 

but doesn't work. please help.

grouping buyer_id , converting meal_type set works:

>>> df.groupby('buyer_id')['meal_type'].apply(set).str.join(' , ')      buyer_id 36             nonveg 65     veg , nonveg 72             nonveg 79     veg , nonveg 139               veg 140    veg , nonveg name: meal_type, dtype: object