How to calculate conditional probability of values in dataframe pandas-python?

Question

I want to calculate conditional probabilites of ratings(\'A\',\'B\',\'C\') in ratings column.

    company     model    rating   type
0   ford       mustang          


        

Answer 1

You need add reindex for add 0 values for missing pairs:

mux = pd.MultiIndex.from_product([df['rating'].unique(), df['type'].unique()])
s = (df.groupby(['rating', 'type']).count() / df.groupby('rating').count())['model']
s = s.reindex(mux, fill_value=0)
print (s)
A  coupe    0.500000
   sedan    0.500000
B  coupe    0.333333
   sedan    0.666667
C  coupe    0.000000
   sedan    1.000000
Name: model, dtype: float64

And another solution, thanks Zero:

s.unstack(fill_value=0).stack()