列标题（如数据透视表）

Question

I am trying to find out the mix of member grades that visit my stores.

import pandas as pd

df=pd.DataFrame({'MbrID':['M1','M2','M3','M4','M5','M6','M7']
                    ,'Store':['PAR','TPM','AMK','TPM','PAR','PAR','AMK']
                    ,'Grade':['A','A','B','A','C','A','C']})
df=df[['MbrID','Store','Grade']]
print(df)

df.groupby('Store').agg({'Grade':pd.Series.nunique})

Below is the dataframe and also the result of groupby function.

How do I produce the result like Excel Pivot table, such that the categories of Grade (A,B,C) is the column headers? This is assuming that I have quite a wide range of member grades.

Answer 1

I think you can use groupby with size and reshaping by unstack :

df1 = df.groupby(['Store','Grade'])['Grade'].size().unstack(fill_value=0)
print (df1)
Grade  A  B  C
Store         
AMK    0  1  1
PAR    2  0  1
TPM    2  0  0

Solution with crosstab :

df2 = pd.crosstab(df.Store, df.Grade)
print (df2)
Grade  A  B  C
Store         
AMK    0  1  1
PAR    2  0  1
TPM    2  0  0

and with pivot_table :

df3 = df.pivot_table(index='Store', 
                     columns='Grade', 
                     values='MbrID', 
                     aggfunc=len,
                     fill_value=0)
print (df3)
Grade  A  B  C
Store         
AMK    0  1  1
PAR    2  0  1
TPM    2  0  0