用于交叉验证模型的predict_proba [英] predict_proba for a cross-validated model

问题描述

我想通过交叉验证从Logistic回归模型预测概率.我知道您可以获取交叉验证分数，但是可以从predict_proba返回值而不是分数吗?

I would like to predict the probability from Logistic Regression model with cross-validation. I know you can get the cross-validation scores, but is it possible to return the values from predict_proba instead of the scores?

# imports
from sklearn.linear_model import LogisticRegression
from sklearn.cross_validation import (StratifiedKFold, cross_val_score,
                                      train_test_split)
from sklearn import datasets

# setup data
iris = datasets.load_iris()
X = iris.data
y = iris.target

# setup model
cv = StratifiedKFold(y, 10)
logreg = LogisticRegression()

# cross-validation scores
scores = cross_val_score(logreg, X, y, cv=cv)

# predict probabilities
Xtrain, Xtest, ytrain, ytest = train_test_split(X, y)
logreg.fit(Xtrain, ytrain)
proba = logreg.predict_proba(Xtest)

推荐答案

现在已作为scikit-learn版本0.18的一部分实现.您可以将方法"字符串参数传递给cross_val_predict方法.文档位于此处.

This is now implemented as part of scikit-learn version 0.18. You can pass a 'method' string parameter to the cross_val_predict method. Documentation is here.

示例:

proba = cross_val_predict(logreg, X, y, cv=cv, method='predict_proba')

还要注意，这是新的sklearn.model_selection包的一部分，因此您将需要此导入:

Also note that this is part of the new sklearn.model_selection package so you will need this import:

from sklearn.model_selection import cross_val_predict

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