Python 'train_test_split' NameError: Not Defined - Solution & Explanation

This error, 'NameError: name 'train_test_split' is not defined', happens because the train_test_split() function isn't available in your current Python environment. This usually means you haven't imported the required library or module that contains it.

The most common cause is that you're likely using the train_test_split function from the scikit-learn library, which is a fundamental tool for machine learning in Python. To fix this, simply import the function before using it:

from sklearn.model_selection import train_test_split

Make sure you place this import statement before any code that uses the train_test_split() function. Once imported, you can use it to split your data into training and testing sets as you intended.

Example:

from sklearn.model_selection import train_test_split

# Your data (replace with your actual data)
X = ...  # Features
y = ...  # Target variable

X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=0)

By following these steps, you can ensure that the train_test_split() function is correctly imported and readily available for use in your Python code.