Change multiple columns values with applymap

We will provide an example of how you can change multiple column values in pandas data frames using the applymap function. Assume that your data frame takes values 1,2,3 and you want to apply the following mapping function:

• If 1 then 0
• If 2 or 3 then 1

df = pd.DataFrame({'A':[1,1,2,2,3,3],
                   'B':[1,2,3,1,2,3]})
df

        A	B
0	1	1
1	1	2
2	2	3
3	2	1
4	3	2
5	3	3

# create the mapping dictionary
d = {1 : 0, 2: 1, 3: 1}

# apply it to all columns
df.applymap(d.get)

        A	B
0	0	0
1	0	1
2	1	1
3	1	0
4	1	1
5	1	1