मॉडल की गुणवत्ता का आकलन

# Create the DMatrix: housing_dmatrix
housing_dmatrix = xgb.DMatrix(data=X, label=y)

# Create the parameter dictionary: params
params = {"objective":"reg:squarederror", "max_depth":4}

# Perform cross-validation: cv_results
cv_results = ____(dtrain=____, params=____, nfold=____, num_boost_round=____, metrics=____, as_pandas=True, seed=123)

# Print cv_results
print(cv_results)

# Extract and print final boosting round metric
print((cv_results["____"]).tail(1))