Scikit-Learn决策树:预测的概率是a还是b? [英] Scikit-Learn Decision Tree: Probability of prediction being a or b?

问题描述

我使用Scikit-Learn有一个基本的决策树分类器:

I have a basic decision tree classifier with Scikit-Learn:

#Used to determine men from women based on height and shoe size

from sklearn import tree

#height and shoe size
X = [[65,9],[67,7],[70,11],[62,6],[60,7],[72,13],[66,10],[67,7.5]]

Y=["male","female","male","female","female","male","male","female"]

#creating a decision tree
clf = tree.DecisionTreeClassifier()

#fitting the data to the tree
clf.fit(X, Y)

#predicting the gender based on a prediction
prediction = clf.predict([68,9])

#print the predicted gender
print(prediction)

当我运行程序时，它总是输出"male"或"female"，但是我如何看待预测是男性还是女性的可能性?例如，上面的预测返回男性"，但是如何获取预测男性的预测概率呢?

When I run the program, it always outputs either "male" or "female", but how would I be able to see the probability of the prediction being male or female? For example, the prediction above returns "male", but how would I get it to print the probability of the prediction being male?

谢谢！

推荐答案

您可以执行以下操作:

from sklearn import tree

#load data
X = [[65,9],[67,7],[70,11],[62,6],[60,7],[72,13],[66,10],[67,7.5]]
Y=["male","female","male","female","female","male","male","female"]

#build model
clf = tree.DecisionTreeClassifier()

#fit
clf.fit(X, Y)

#predict
prediction = clf.predict([[68,9],[66,9]])

#probabilities
probs = clf.predict_proba([[68,9],[66,9]])

#print the predicted gender
print(prediction)
print(probs)

理论

clf.predict_proba(X)的结果是:预测类别概率，它是叶子中同一类别的样本的分数.

The result of clf.predict_proba(X) is: The predicted class probability which is the fraction of samples of the same class in a leaf.

结果解释:

第一个 print 返回 ['male''male'] ，因此数据 [[68,9]，[66,9]] 被预测为 males .

The first print returns ['male' 'male'] so the data [[68,9],[66,9]] are predicted as males.

第二个 print 返回:

[[0. 1.][0. 1.]]

这意味着数据被预测为男性，并且由第二列中的数据进行报告.

要查看类的顺序，请使用: clf.classes _

这将返回: ['female'，'male']

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