name train_test_split is not defined

The error message "name 'train_test_split' is not defined" usually occurs when you are trying to use the train_test_split function from scikit-learn library without importing it first. To resolve this error, you need to import the train_test_split function from scikit-learn as follows:

from sklearn.model_selection import train_test_split

Once you have imported train_test_split, you can use it to split your data into training and test sets. For example:

X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=42)

This will split your data into 80% training and 20% test sets, with a random state of 42