Evalueer de trainingsfout

Je gaat nu de RMSE op de trainingset berekenen van de regressieboom dt die je in een eerdere oefening hebt aangemaakt.

Naast dt zijn X_train en y_train beschikbaar in je werkruimte.

Let op: in scikit-learn kun je de MSE van een model als volgt berekenen:

MSE_model = mean_squared_error(y_true, y_predicted)

waarbij we de functie mean_squared_error uit de module metrics gebruiken en de ware labels y_true als eerste argument doorgeven, en de door het model voorspelde labels y_predicted als tweede argument.

Deze oefening maakt deel uit van de cursus

Machine Learning met boomgebaseerde modellen in Python

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Oefeninstructies

Importeer mean_squared_error als MSE uit sklearn.metrics.
Fit dt op de trainingset.
Voorspel de trainingslabels met dt en sla het resultaat op in y_pred_train.
Bereken de RMSE op de trainingset van dt en sla deze op in RMSE_train.

Praktische interactieve oefening

Probeer deze oefening eens door deze voorbeeldcode in te vullen.

# Import mean_squared_error from sklearn.metrics as MSE
____

# Fit dt to the training set
____.____(____, ____)

# Predict the labels of the training set
____ = ____.____(____)

# Evaluate the training set RMSE of dt
____ = (____(____, ____))**(___)

# Print RMSE_train
print('Train RMSE: {:.2f}'.format(RMSE_train))

Code bewerken en uitvoeren

Deze oefening maakt deel uit van de cursus

Machine Learning met boomgebaseerde modellen in Python

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Begin de cursus gratis

Classification and Regression Trees (CART) are a set of supervised learning models used for problems involving classification and regression. In this chapter, you'll be introduced to the CART algorithm.

Exercise 1: Decision tree for classification Exercise 2: Train your first classification tree Exercise 3: Evaluate the classification tree Exercise 4: Logistic regression vs classification tree Exercise 5: Classification tree Learning Exercise 6: Growing a classification tree Exercise 7: Using entropy as a criterion Exercise 8: Entropy vs Gini index Exercise 9: Decision tree for regression Exercise 10: Train your first regression tree Exercise 11: Evaluate the regression tree Exercise 12: Linear regression vs regression tree

The bias-variance tradeoff is one of the fundamental concepts in supervised machine learning. In this chapter, you'll understand how to diagnose the problems of overfitting and underfitting. You'll also be introduced to the concept of ensembling where the predictions of several models are aggregated to produce predictions that are more robust.

Exercise 1: Generalisatiefout Exercise 2: Complexiteit, bias en variantie Exercise 3: Overfitting en underfitting Exercise 4: Diagnoseer bias- en variantieproblemen Exercise 5: Het model instantiëren Exercise 6: Evalueer de 10-voudige CV-fout Exercise 7: Evalueer de trainingsfout

Huidige oefening

Exercise 8: Hoge bias of hoge variance?Exercise 9: Ensemble learning Exercise 10: Definieer het ensemble Exercise 11: Beoordeel afzonderlijke classificatiemodellen Exercise 12: Betere prestaties met een Voting Classifier

Bagging is an ensemble method involving training the same algorithm many times using different subsets sampled from the training data. In this chapter, you'll understand how bagging can be used to create a tree ensemble. You'll also learn how the random forests algorithm can lead to further ensemble diversity through randomization at the level of each split in the trees forming the ensemble.

Exercise 1: Bagging Exercise 2: Define the bagging classifier Exercise 3: Evaluate Bagging performance Exercise 4: Out of Bag Evaluation Exercise 5: Prepare the ground Exercise 6: OOB Score vs Test Set Score Exercise 7: Random Forests (RF)Exercise 8: Train an RF regressor Exercise 9: Evaluate the RF regressor Exercise 10: Visualizing features importances

Boosting refers to an ensemble method in which several models are trained sequentially with each model learning from the errors of its predecessors. In this chapter, you'll be introduced to the two boosting methods of AdaBoost and Gradient Boosting.

Exercise 1: Adaboost Exercise 2: Define the AdaBoost classifier Exercise 3: Train the AdaBoost classifier Exercise 4: Evaluate the AdaBoost classifier Exercise 5: Gradient Boosting (GB)Exercise 6: Define the GB regressor Exercise 7: Train the GB regressor Exercise 8: Evaluate the GB regressor Exercise 9: Stochastic Gradient Boosting (SGB)Exercise 10: Regression with SGB Exercise 11: Train the SGB regressor Exercise 12: Evaluate the SGB regressor

The hyperparameters of a machine learning model are parameters that are not learned from data. They should be set prior to fitting the model to the training set. In this chapter, you'll learn how to tune the hyperparameters of a tree-based model using grid search cross validation.

Exercise 1: Tuning a CART's Hyperparameters Exercise 2: Tree hyperparameters Exercise 3: Set the tree's hyperparameter grid Exercise 4: Search for the optimal tree Exercise 5: Evaluate the optimal tree Exercise 6: Tuning a RF's Hyperparameters Exercise 7: Random forests hyperparameters Exercise 8: Set the hyperparameter grid of RF Exercise 9: Search for the optimal forest Exercise 10: Evaluate the optimal forest Exercise 11: Congratulations!