How to multiply two or multiple columns in a pandas DataFrame
In this article, you will learn how to multiply multiple columns in a pandas Dataframe
Let’s first create random Pandas DataFrame (you can also import pandas DataFrame from file)
import pandas as pd
# Create DataFrame
df = pd.DataFrame({ 'col1':[10, 11, 13, 25, 282],
'col2':[2, 3, 4, 5, 8],
'col3':[0.1, 0.2, 0.3, 0.4, 0.5],
'col4': ['A', 'B', 'B', 'B', 'A']})
df
#output
col1 col2 col3 col4
0 10 2 0.1 A
1 11 3 0.2 B
2 13 4 0.3 B
3 25 5 0.4 B
4 282 8 0.5 A
Multiply two columns
Multiply two columns (col1 and col2) in a df Dataframe,
# multiply and create a new column in df
df['col5'] = df['col1'] * df['col2'] # same as df['col5'] = df.col1 * df.col2
df
# output
df
col1 col2 col3 col4 col5
0 10 2 0.1 A 20
1 11 3 0.2 B 33
2 13 4 0.3 B 52
3 25 5 0.4 B 125
4 282 8 0.5 A 2256
The col5 contains the multiplication values
Multiply multiple columns
As similar to two columns, you can also multiply multiple columns in a pandas Dataframe. Here, you will use the Dataframe
multiply function, which works like
you are multiplying two different Dataframes
# multiply col1, col2, and col3
df['col5'] = pd.DataFrame(df['col1'] * df['col2']).multiply(df['col3'], axis=0)
df
#output
df
col1 col2 col3 col4 col5
0 10 2 0.1 A 2.0
1 11 3 0.2 B 6.6
2 13 4 0.3 B 15.6
3 25 5 0.4 B 50.0
4 282 8 0.5 A 1128.0
The col5 contains the multiplication values of col1, col2, and col3
Multiply multiple columns by a single column
You can also multiply multiple columns in a pandas Dataframe by values in another single column,
# multiply col1 and col2, by values in col3
df[['col1', 'col2']].multiply(df['col3'], axis=0)
# output
col1 col2
0 1.0 0.2
1 2.2 0.6
2 3.9 1.2
3 10.0 2.0
4 141.0 4.0
Multiply single or multiple columns by a specific value
You can multiply single or multiple Dataframe columns by any specific value,
Multiply a single column by a specific value,
# multiply col1 by 5
df['col5'] = df['col1'] * 5 # same as df['col5'] = df.col1 * 5
df
#output
df
col1 col2 col3 col4 col5
0 10 2 0.1 A 50
1 11 3 0.2 B 55
2 13 4 0.3 B 65
3 25 5 0.4 B 125
4 282 8 0.5 A 1410
Multiply two columns by a specific value,
# multiply col1 and col2 by 5
df[['col1', 'col2']] * 5
#output
col1 col2
0 50 10
1 55 15
2 65 20
3 125 25
4 1410 40
Multiply columns based on a condition
You can also multiply the two columns of a pandas DataFrame based on a conditional value in another column
For example, multiply col1 and col3 where the col4 has B value,
df['col5'] = df.query('col4=="B"').col1 * df.query('col4=="B"').col3
df
# output
col1 col2 col3 col4 col5
0 10 2 0.1 A NaN
1 11 3 0.2 B 2.2
2 13 4 0.3 B 3.9
3 25 5 0.4 B 10.0
4 282 8 0.5 A NaN
Learn more about how to query pandas DataFrame for conditional selection of rows
Enhance your skills with courses on Python and pandas
- Python for Data Analysis: Pandas & NumPy
- Mastering Data Analysis with Pandas: Learning Path Part 1
- Data Analysis Using Python
- Python for Everybody Specialization
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