子组 pandas 中值的计数频率

Question

I am trying to count the number of True and False values in a pandas df like this. However, I'm having trouble first using groupby() to isolate my groups before using count().

Here's a toy example of my df in which A, B, and C are columns:

A   B   C
1   a   true
1   a   true
1   b   true
1   b   false
2   c   false
2   c   true
2   c   true
2   d   false

Does anyone have help? Here's my desired output:

B   true   false
a   2      0
b   1      1
c   1      2
d   0      1

I'm new to coding in python, so many thanks in advance!

Answer 1

We can try crosstab

pd.crosstab(df.B,df.C)
C  False  True 
B              
a      0      2
b      1      1
c      1      2
d      1      0