参考文章:https://scikit-learn.org/stable/modules/model_evaluation.html#scoring-parameter
默认为None
其他选项如下:
1.accuracy:返回的值是正确率,等同于下面的方式。
from sklearn.metrics import accuracy_score
y_pred=[0,2,1,3]
y_true=[0,1,2,3]
accuracy_score(y_true,y_pred)
0.5
accuracy_score(y_true,y_pred,normalize=False)
2.balanced_accuracy:用于不平衡的数据(to deal with imbalanced datasets,也就是不同类的样本差距较大的数据)。结果最好时值为1,结果不好时值为0,可能会根据样本权重做调整。(The best value is 1 and the worst value is 0 when adjusted=False.)
from sklearn.metrics import balanced_accuracy_score
y_true=[0,1,0,0,1,0]
y_pred=[0,1,0,0,0,1]
balanced_accuracy_score(y_true,y_pred)
0.625
本来值应该是 4/6=0.6666666666666666,经过“balanced”后,值变为0.625