使用贪心算法寻优的随机森林分类python代码
时间: 2023-07-05 11:35:56 浏览: 51
以下是使用贪心算法寻优的随机森林分类的Python代码示例:
```python
from sklearn.ensemble import RandomForestClassifier
import numpy as np
import pandas as pd
# 导入数据集
data = pd.read_csv('data.csv')
X = data.iloc[:, :-1].values
y = data.iloc[:, -1].values
# 定义随机森林分类器
rf = RandomForestClassifier(n_estimators=10, criterion='entropy', random_state=42)
# 定义特征选择函数
def greedy_feature_selection(X, y, rf):
selected_features = []
best_score = 0
while True:
scores = []
for i in range(X.shape[1]):
if i not in selected_features:
features = selected_features + [i]
X_new = X[:, features]
score = np.mean(cross_val_score(rf, X_new, y, cv=5))
scores.append((score, i))
scores.sort(reverse=True)
if scores[0][0] > best_score:
best_score, best_feature = scores[0]
selected_features.append(best_feature)
else:
break
return selected_features
# 进行特征选择
selected_features = greedy_feature_selection(X, y, rf)
# 重新定义随机森林分类器,只使用选择的特征
rf_new = RandomForestClassifier(n_estimators=10, criterion='entropy', random_state=42)
X_new = X[:, selected_features]
# 进行交叉验证
scores = cross_val_score(rf_new, X_new, y, cv=5)
print('Accuracy: %0.2f (+/- %0.2f)' % (scores.mean(), scores.std() * 2))
```
在上面的代码中,我们首先导入数据集,然后定义了一个随机森林分类器。接着,定义了一个特征选择函数,使用贪心算法寻优来选择最佳特征子集。最后,重新定义了一个随机森林分类器,只使用选择的特征,然后进行交叉验证,并输出准确率。