Pandas DataFrame – Replace Multiple Values

Pandas DataFrame – Replace Multiple Values

To replace multiple values in a DataFrame, you can use DataFrame.replace() method with a dictionary of different replacements passed as argument.

Examples

1. Replace multiple values in a column

The syntax to replace multiple values in a column of DataFrame is

DataFrame.replace({'column_name' : { old_value_1 : new_value_1, old_value_2 : new_value_2}})

In the following example, we will use replace() method to replace 1 with 11 and 2 with 22 in column a.

import pandas as pd

df = pd.DataFrame([
	[4, -9, 8],
	[1, 2, -4],
    [2, 2, -8],
    [0, 7, -4],
	[2, 5, 1]],
	columns=['a', 'b', 'c'])

df = df.replace({'a':{1:11, 2:22}})
print(df)

Output

    a  b  c
0   4 -9  8
1  11  2 -4
2  22  2 -8
3   0  7 -4
4  22  5  1

2. Replace multiple values in multiple columns

The syntax to replace multiple values in multiple columns of DataFrame is

DataFrame.replace({'column_name_1' : { old_value_1 : new_value_1, old_value_2 : new_value_2},
                   'column_name_2' : { old_value_1 : new_value_1, old_value_2 : new_value_2}})

In the following example, we will use replace() method to replace 1 with 11 and 2 with 22 in column a; 5 with 55 and 2 with 22 in column b.

import pandas as pd

df = pd.DataFrame([
	[4, -9, 8],
	[1, 2, -4],
    [2, 2, -8],
    [0, 7, -4],
	[2, 5, 1]],
	columns=['a', 'b', 'c'])

df = df.replace({'a':{1:11, 2:22}, 'b':{5:55, 2:22}})
print(df)

Output

    a   b  c
0   4  -9  8
1  11  22 -4
2  22  22 -8
3   0   7 -4
4  22  55  1

Summary

In this tutorial of Python Examples, we learned how to replace multiple values in Pandas DataFrame in one or more columns.