从一列的值向DataFrame添加新列

Question

I have a pandas DataFrame, there is a column with values like a,b,c ie string splited by ','. Now I want to create new columns, for example, for a,b,c there would be new column a, column b, column c. then the data with a,b,c would get a value of true on the three columns, the data with a,b,e would get true on columns a and b but false on c, maybe it is more clearly to see the picture below. How to do this?

Answer 1

Use str.get_dummies with cast to bool by astype and add column B by join :

df1 = df['A'].str.get_dummies(',').astype(bool).join(df['B'])
print (df1)
       a     b     c      f  B
0   True  True  True  False  3
1  False  True  True   True  4

More general solution with pop for extract column A :

df = pd.DataFrame({'A':['a,b,c','b,c,f'], 'B':[3,4], 'C':[7,3]})
print (df)
       A  B  C
0  a,b,c  3  7
1  b,c,f  4  3

df1 = df.pop('A').str.get_dummies(',').astype(bool).join(df)
print (df1)
       a     b     c      f  B  C
0   True  True  True  False  3  7
1  False  True  True   True  4  3