Tuning max_depth

In this exercise, your job is to tune max_depth, which is the parameter that dictates the maximum depth that each tree in a boosting round can grow to. Smaller values will lead to shallower trees, and larger values to deeper trees.

Deze oefening maakt deel uit van de cursus

Extreme Gradient Boosting with XGBoost

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Oefeninstructies

Create a list called max_depths to store the following "max_depth" values: 2, 5, 10, and 20.
Iterate over your max_depths list using a for loop.
Systematically vary "max_depth" in each iteration of the for loop and perform 2-fold cross-validation with early stopping (5 rounds), 10 boosting rounds, a metric of "rmse", and a seed of 123. Ensure the output is a DataFrame.

Praktische interactieve oefening

Probeer deze oefening eens door deze voorbeeldcode in te vullen.

# Create your housing DMatrix
housing_dmatrix = xgb.DMatrix(data=X,label=y)

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

# Create list of max_depth values
max_depths = ____
best_rmse = []

# Systematically vary the max_depth
for curr_val in ____:

    params["____"] = ____
    
    # Perform cross-validation
    cv_results = ____
    
    
    
    # Append the final round rmse to best_rmse
    best_rmse.append(cv_results["test-rmse-mean"].tail().values[-1])

# Print the resultant DataFrame
print(pd.DataFrame(list(zip(max_depths, best_rmse)),columns=["max_depth","best_rmse"]))

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