A **trimmed mean** is the mean of a dataset that has been calculated after removing a specific percentage of the smallest and largest values from the dataset.

The easiest way to calculate a trimmed mean in Python is to use the **trim_mean()** function from the SciPy library.

This function uses the following basic syntax:

from scipy import stats #calculate 10% trimmed mean stats.trim_mean(data, 0.1)

The following examples show how to use this function to calculate a trimmed mean in practice.

**Example 1: Calculate Trimmed Mean of Array**

The following code shows how to calculate a 10% trimmed mean for an array of data:

from scipy import stats #define data data = [22, 25, 29, 11, 14, 18, 13, 13, 17, 11, 8, 8, 7, 12, 15, 6, 8, 7, 9, 12] #calculate 10% trimmed mean stats.trim_mean(data, 0.1) 12.375

The 10% trimmed mean is **12.375**.

This is the mean of the dataset after the smallest 10% and largest 10% of values have been removed from the dataset.

**Example 2: Calculate Trimmed Mean of Column in Pandas**

The following code shows how to calculate a 5% trimmed mean for a specific column in a pandas DataFrame:

from scipy import stats import pandas as pd #define DataFrame df = pd.DataFrame({'points': [25, 12, 15, 14, 19, 23, 25, 29], 'assists': [5, 7, 7, 9, 12, 9, 9, 4], 'rebounds': [11, 8, 10, 6, 6, 5, 9, 12]}) #calculate 5% trimmed mean of points stats.trim_mean(df.points, 0.05) 20.25

The 5% trimmed mean of the values in the ‘points’ column is **20.25**.

This is the mean of the ‘points’ column after the smallest 5% and largest 5% of values have been removed.

**Example 3: Calculate Trimmed Mean of Multiple Columns**

The following code shows how to calculate a 5% trimmed mean for multiple columns in a pandas DataFrame:

from scipy import stats import pandas as pd #define DataFrame df = pd.DataFrame({'points': [25, 12, 15, 14, 19, 23, 25, 29], 'assists': [5, 7, 7, 9, 12, 9, 9, 4], 'rebounds': [11, 8, 10, 6, 6, 5, 9, 12]}) #calculate 5% trimmed mean of 'points' and 'assists' columns stats.trim_mean(df[['points', 'assists']], 0.05) array([20.25, 7.75])

From the output we can see:

- The 5% trimmed mean of the ‘points’ column is
**20.25**. - The 5% trimmed mean of the ‘assists’ column is
**7.75**.

**Note**: You can find the complete documentation for the **trim_mean()** function here.

**Additional Resources**

How to Calculate a Trimmed Mean by Hand

Trimmed Mean Calculator