Grouping and Computing Frequency ,Pandas

Question

I have a dataframe :

df = pd.DataFrame({'Type' : ['Pokemon', 'Pokemon', 'Bird', 'Pokemon', 'Bird', 'Pokemon', 'Pokemon', 'Bird'],'Name' : ['Jerry', 'Jerry', 'Flappy Bird', 'Mudkip','Pigeon', 'Mudkip', 'Jerry', 'Pigeon']})

and i need to group the observations w.r.t their types i.e all pokemon types together with their respective names . And i need to add another column which has the frequency of occurrence of the names in the types. It should look like :

Type         Name     Frequency   
Pokemon      Jerry        3 
             Mudkip       2    

Bird         Pigeon       2  
           Flappy Bird    1  

I used :

data2 = df.groupby(['Type']) 

but that doesn't group it the way it needs to be.
Please help.

Answer 1

I think you want to group on both 'Type' and 'Name':

print df.groupby(['Type','Name']).size()

Type     Name       
Bird     Flappy Bird    1
         Pigeon         2
Pokemon  Jerry          3
         Mudkip         2

Or if it is important to have the column named 'Frequency', you could do something like the following:

print df.groupby(['Type','Name'])['Type'].agg({'Frequency':'count'})

                     Frequency
Type    Name                  
Bird    Flappy Bird          1
        Pigeon               2
Pokemon Jerry                3
        Mudkip               2