Pandas DataFrame round() Method

Preparation

Before any data manipulation can occur, two (2) new libraries will require installation.

• The Pandas library enables access to/from a DataFrame.
• The NumPy library supports multi-dimensional arrays and matrices in addition to a collection of mathematical functions.

To install these libraries, navigate to an IDE terminal. At the command prompt ($), execute the code below. For the terminal used in this example, the command prompt is a dollar sign ($). Your terminal prompt may be different.

$ pip install pandas

Hit the <Enter> key on the keyboard to start the installation process.

$ pip install numpy

Hit the <Enter> key on the keyboard to start the installation process.

If the installations were successful, a message displays in the terminal indicating the same.

Feel free to view the PyCharm installation guide for the required libraries.

• How to install Pandas on PyCharm
• How to install Numpy on PyCharm

Add the following code to the top of each code snippet. This snippet will allow the code in this article to run error-free.

import pandas as pd
import numpy as np 

DataFrame round()

The round() method rounds the DataFrame output to a specified number of decimal places.

The syntax for this method is as follows:

DataFrame.round(decimals=0, *args, **kwargs)

For this example, the Bank of Canada’s mortgage rates over three (3) months display and round to three (3) decimal places.

Code Example 1

df = pd.DataFrame([(2.3455, 1.7487, 2.198)], columns=['Month 1', 'Month 2', 'Month 3']) 
result = df.round(3)
print(result)

• Line [1] creates a DataFrame complete with column names and saves it to df.
• Line [2] rounds the mortgage rates to three (3) decimal places. This output saves to the result variable.
• Line [3] outputs the result to the terminal.

Output

Another way to perform the same task is with a Lambda!

Code Example 2

df = pd.DataFrame([(2.3455, 1.7487, 2.198)], 
                  columns=['Month 1', 'Month 2', 'Month 3']) 
result = df.apply(lambda x: round(x, 3))
print(result)

• Line [1] creates a DataFrame complete with column names and saves it to df.
• Line [2] rounds the mortgage rates to three (3) decimal places using a Lambda. This output saves to the result variable.
• Line [3] outputs the result to the terminal.

💡 Note: The output is identical to that of the above.

More Pandas DataFrame Methods

Feel free to learn more about the previous and next pandas DataFrame methods (alphabetically) here:

Also, check out the full cheat sheet overview of all Pandas DataFrame methods.