用BayesSearchCV对CatBoostClassifier (多类分类)进行超参数整定时出错

Question

我正在尝试用CatBoostClassifier调优多类分类的超参数，但是得到的错误。

ValueError: multiclass format is not supported

我的目标变量包含(0,1,2,3)

请检查下面的代码，我已经实现了。

  accuracy = make_scorer(accuracy_score, greater_is_better=True, needs_threshold=True)
skf = StratifiedKFold(n_splits=5, shuffle=True, random_state=42)

clf = CatBoostClassifier(thread_count=2, loss_function='MultiClass', eval_metric='Accuracy', leaf_estimation_method='Newton',  od_type = 'Iter', verbose= False)

# Defining your search space
search_spaces = {'iterations': Integer(10, 2000),
                 'depth': Integer(1, 12),
                 'learning_rate': Real(0.01, 1.0, 'log-uniform'),
                 'random_strength': Real(1e-9, 10, 'log-uniform'),
                 'bagging_temperature': Real(0.0, 1.0),
                 'border_count': Integer(1, 255),
                 'l2_leaf_reg': Integer(2, 30)}

# Setting up BayesSearchCV
opt = BayesSearchCV(clf,
                    search_spaces,
                    scoring=accuracy,
                    cv=skf,
                    n_iter=100,
                    n_jobs=1, 
                    return_train_score=False,
                    refit=True,
                    optimizer_kwargs={'base_estimator': 'GP'},
                    random_state=42)
opt.fit(X_train, y_train)

如果我的问题需要更多的细节，请告诉我。请帮我解决这个问题。谢谢!

Answer 1

尝试将objective = 'multi:softmax'添加到分类器并设置classes_count