1. The Scikit-Learn API

The Universal API

Scikit-Learn (sklearn) is beautiful because of its consistency. All models follow the same interface.

python
from sklearn.linear_model import LinearRegression

# 1. Instantiate
model = LinearRegression()

# 2. Fit (Train)
model.fit(X_train, y_train)

# 3. Predict
predictions = model.predict(X_test)

Hyperparameters vs Parameters

• Hyperparameters: Settings YOU choose (e.g., Tree Depth). Set during instantiation.
• Parameters: Values the MODEL learns (e.g., Weights). Available after .fit().