我正在尝试在python中执行10倍交叉验证。我知道如何计算混淆矩阵和拆分测试的报告(例如拆分80%的训练和20%的测试(。但问题是,我不知道如何计算混淆矩阵,并为每个折叠报告——例如,当折叠10时,我只知道平均精度的代码。
这里是一个可重复的例子,使用癌症数据和3倍CV简化:
from sklearn.datasets import load_breast_cancer
from sklearn.tree import DecisionTreeClassifier
from sklearn.metrics import confusion_matrix, classification_report
from sklearn.model_selection import KFold
X, y = load_breast_cancer(return_X_y=True)
n_splits = 3
kf = KFold(n_splits=n_splits, shuffle=True)
model = DecisionTreeClassifier()
for train_index, val_index in kf.split(X):
model.fit(X[train_index], y[train_index])
pred = model.predict(X[val_index])
print(confusion_matrix(y[val_index], pred))
print(classification_report(y[val_index], pred))
结果得到3个混淆矩阵&分类报告,每个CV折叠一份:
[[ 63 9]
[ 10 108]]
precision recall f1-score support
0 0.86 0.88 0.87 72
1 0.92 0.92 0.92 118
micro avg 0.90 0.90 0.90 190
macro avg 0.89 0.90 0.89 190
weighted avg 0.90 0.90 0.90 190
[[ 66 8]
[ 6 110]]
precision recall f1-score support
0 0.92 0.89 0.90 74
1 0.93 0.95 0.94 116
micro avg 0.93 0.93 0.93 190
macro avg 0.92 0.92 0.92 190
weighted avg 0.93 0.93 0.93 190
[[ 59 7]
[ 8 115]]
precision recall f1-score support
0 0.88 0.89 0.89 66
1 0.94 0.93 0.94 123
micro avg 0.92 0.92 0.92 189
macro avg 0.91 0.91 0.91 189
weighted avg 0.92 0.92 0.92 189