混淆矩阵轴的正确标记

Question

我写了下面的代码来生成混淆矩阵

from sklearn.naive_bayes import MultinomialNB
mnb=MultinomialNB()
mnb.fit(X_train,Y_train)
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X_test = [str (item) for item in X_test]

Y_pred = mnb.predict(vec.transform(X_test))
from sklearn.metrics import confusion_matrix
mat = confusion_matrix(Y_test, Y_pred)
print(mat)
names =[ "non-spam", "spam"]
print(names)
sns.heatmap(mat, square=True, annot=True, fmt='d', cbar=False,
            xticklabels=names, yticklabels=names)
plt.xlabel('Actual [Truth]')
plt.ylabel('Predicted')
plt.show()

它生成了以下混淆矩阵：

我不确定轴是否标记正确
IE。如果x轴应该是Actual而y轴应该是predicted
或者反过来

Answer 1

根据 scikit=learn 文档，https://scikit-learn.org/stable/modules/generated/sklearn.metrics.confusion_matrix.html，第一个调用参数应该是真实值，第二个调用参数应该是通过分类器的预测值。

如果是这样，那么混淆矩阵的 return 参数应该包含包含真实类的行，并且列应该是预测的类.

基于此，我认为您的标签落后了。另请参阅示例 https://scikit-learn.org/stable/auto_examples/miscellaneous/plot_display_object_visualization.html#sphx-glr-auto-examples-miscellaneous-plot-display-object-visualization-py

混淆矩阵轴的正确标记

Correct labelling of confusion matrix axis

machine-learning

confusion-matrix

scikit-learn