sklearn评估k折交叉验证作图
时间: 2023-12-12 16:05:09 浏览: 24
要使用scikit-learn(sklearn)来评估k折交叉验证并作图,你可以按照以下步骤进行操作:
1. 导入必要的库:
```python
import numpy as np
import matplotlib.pyplot as plt
from sklearn.datasets import make_classification
from sklearn.model_selection import cross_val_score
```
2. 创建一个分类数据集(这里以make_classification为例):
```python
X, y = make_classification(n_samples=1000, n_features=20, random_state=42)
```
3. 定义一个函数,该函数将用于评估给定模型的交叉验证得分,并返回平均得分和标准差:
```python
def evaluate_model(model):
scores = cross_val_score(model, X, y, cv=10) # 这里使用10折交叉验证
return np.mean(scores), np.std(scores)
```
4. 创建一个模型对象并调用evaluate_model函数来评估模型:
```python
from sklearn.linear_model import LogisticRegression
model = LogisticRegression()
mean_score, std_score = evaluate_model(model)
print("Mean Score:", mean_score)
print("Standard Deviation:", std_score)
```
5. 可选:创建一个函数来绘制不同k值下的交叉验证得分图表:
```python
def plot_cross_val_scores(k_range):
mean_scores = []
std_scores = []
for k in k_range:
model = LogisticRegression()
scores = cross_val_score(model, X, y, cv=k)
mean_scores.append(np.mean(scores))
std_scores.append(np.std(scores))
plt.errorbar(k_range, mean_scores, yerr=std_scores)
plt.xlabel('Number of Folds (k)')
plt.ylabel('Mean Cross-validated Accuracy')
plt.title('Cross-validation scores for different k')
plt.show()
```
6. 调用plot_cross_val_scores函数来绘制不同k值下的交叉验证得分图表:
```python
k_values = [3, 5, 7, 10]
plot_cross_val_scores(k_values)
```
这样,你就可以使用scikit-learn评估k折交叉验证并作图了。请根据你的实际需求进行适当的修改和调整。