使用交叉表在 Pandas 中聚合具有不同聚合函数的多个列

Question

I have a dataframe of the below format. Let us call it df

flag1	flag2	type	count1	count2
a	x	new	10	2
a	y	old	40	5
a	x	old	50	6
a	y	new	15	1

I am trying to get the following format. (I could not merge the adjacent cells of count1 and count2)

		count1		count2
		new	old	new	old
a	x	10	50	2	6
a	y	15	40	1	5

I tried the following when i had to do the aggregate on only one column (count1) and the following worked:

pd.crosstab([df.flag1,df.flag2], df.type, values=df.count1, aggfunc='sum') 

But since i want two columns of data, both count1 and count2, I tried the following but did not work out

pd.crosstab([df.flag1,df.flag2], df.type, values=[df.count1,df.count2], aggfunc=['sum','sum']) #trial1
pd.crosstab([df.flag1,df.flag2], df.type, values=[df.count1,df.count2], aggfunc='sum') #trial2

None of them worked.

Extension : I should be able use different functions on the different columns. say sum on count1 and nunique on count2 or sum on count1 and mean on count2

Answer 1

I think crosstab is not possible use here, alternative is DataFrame.pivot_table :

df = df.pivot_table(index=['flag1','flag2'], 
                    columns='type', 
                    aggfunc={'count1':'sum', 'count2':'nunique'})
print (df)
            count1     count2    
type           new old    new old
flag1 flag2                      
a     x         10  50      1   1
      y         15  40      1   1

Another alternative with aggregation:

df = (df.groupby(['flag1','flag2','type'])
        .agg({'count1':'sum', 'count2':'nunique'})
        .unstack())
print (df)
            count1     count2    
type           new old    new old
flag1 flag2                      
a     x         10  50      1   1
      y         15  40      1   1