from sklearn.model_selection import train_test_split

# Split data: some for learning, some for testing
X_train, X_test, y_train, y_test = train_test_split(heights.reshape(-1,1), weights, test_size=0.5)

model.fit(X_train, y_train)  # Learn from training data
score = model.score(X_test, y_test)  # Test on unseen data
print(f"Model accuracy: {score:.2f}")