使用sklearn的AdaBoost和GradientBoost对乳腺癌数据进行分类,要求:导入乳腺癌数据集,测试learning_rate参数对分类效果的影响,测试nestimators参数对分类效果的影响。
时间: 2024-05-09 20:22:10 浏览: 128
Ada_Boost.rar_Adaboost分类_Boost_adaboost_adaboost matlab_matlab数据
好的,让我来回答您的问题。首先,要使用sklearn加载乳腺癌数据集,可以使用以下代码:
```python
from sklearn.datasets import load_breast_cancer
data = load_breast_cancer()
X, y = data.data, data.target
```
这里我们将数据分为X和y,X代表输入特征,y代表分类标签。接下来,我们可以用AdaBoost和GradientBoost来分类乳腺癌数据集。
```python
from sklearn.ensemble import AdaBoostClassifier, GradientBoostingClassifier
from sklearn.metrics import accuracy_score
from sklearn.model_selection import train_test_split
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.3, random_state=42)
# AdaBoost分类器
ada_clf = AdaBoostClassifier(n_estimators=50, learning_rate=0.1, random_state=42)
ada_clf.fit(X_train, y_train)
y_pred = ada_clf.predict(X_test)
print("AdaBoost准确率:", accuracy_score(y_test, y_pred))
# GradientBoost分类器
gb_clf = GradientBoostingClassifier(n_estimators=50, learning_rate=0.1, random_state=42)
gb_clf.fit(X_train, y_train)
y_pred = gb_clf.predict(X_test)
print("GradientBoost准确率:", accuracy_score(y_test, y_pred))
```
在代码中,我们首先将数据集拆分为训练集和测试集。然后,使用AdaBoost和GradientBoost的sklearn分类器进行分类。在这里,我们设置了n\_estimators和learning\_rate两个超参数。其中,n\_estimators代表弱分类器的数量,learning\_rate代表我们在每次迭代中更新弱分类器权重的程度。接下来,我们测试learning\_rate和n\_estimators对分类效果的影响。
```python
n_estimators_list = [10, 20, 30, 40, 50]
learning_rate_list = [0.01, 0.05, 0.1, 0.15, 0.2]
for n_estimators in n_estimators_list:
for learning_rate in learning_rate_list:
ada_clf = AdaBoostClassifier(n_estimators=n_estimators, learning_rate=learning_rate, random_state=42)
ada_clf.fit(X_train, y_train)
y_pred = ada_clf.predict(X_test)
accuracy = accuracy_score(y_test, y_pred)
print("AdaBoost with n_estimators=%d and learning_rate=%.2f accuracy: %.2f%%" % (n_estimators, learning_rate, accuracy * 100))
gb_clf = GradientBoostingClassifier(n_estimators=n_estimators, learning_rate=learning_rate, random_state=42)
gb_clf.fit(X_train, y_train)
y_pred = gb_clf.predict(X_test)
accuracy = accuracy_score(y_test, y_pred)
print("GradientBoost with n_estimators=%d and learning_rate=%.2f accuracy: %.2f%%" % (n_estimators, learning_rate, accuracy * 100))
```
在上面的代码中,我们对n\_estimators和learning\_rate进行了多次循环。每次循环调用AdaBoost和GradientBoost分类器,计算得到分类精度(即准确率)。最后,我们输出n\_estimators和learning\_rate的不同值对应的分类精度,并找到最佳的超参数组合。
希望以上解答对您有所帮助。
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