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机器学习历程——人工智能基础与应用导论 专题篇(Sklearn)(2)

大柚子top 2022-04-30 阅读 36

目录

一、回顾概念

1、准确率

2、精确率

3、召回率

4、F1

5、ACU

二、自定义TP,FP,TN,FN,accuracy,precision,recall,f1-score


一、回顾概念

TP:预测为正向(P),实际上预测正确(T),即判断为正向的正确率;

TN:预测为负向(N),实际上预测正确(T),即判断为负向的正确率;

FP:预测为正向(P),实际上预测错误(F),误报率,即把负向判断成了正向;

FN:预测为负向(N),实际上预测错误(F),漏报率,即把正向判断称了负向;

y_true = [0, 1, 1, 0] #真实值
y_pred = [1, 1, 1, 0] #预测值

1、准确率

Accuracy=(TP+TN)/(TP+FP+TN+FN), 即预测正确的比上全部数据。

from sklearn.metrics import accuracy_score
accuracy = accuracy_score(y_true, y_pred)

2、精确率

Precision=TP /(TP+FP),即在预测为正向的数据中,有多少预测正确了。

from sklearn.metrics import precision_score
p = precision_score(y_true, y_pred)

3、召回率

Recall=TP /(TP+FN),即在所有正向的数据中,有多少预测正确了。

from sklearn.metrics import recall_score
r = recall_score(y_true, y_pred)

4、F1

from sklearn.metrics import f1_score
f1score = f1_score(y_true, y_pred)

5、ACU

from sklearn.metrics import roc_auc_score
AUC = roc_auc_score(y_true, y_pred)

二、自定义TP,FP,TN,FN,accuracy,precision,recall,f1-score

y_true = np.array([0,1,1,0,1,0])
y_pred = np.array([1,1,0,0,1,0])

TP = np.sum(np.logical_and(np.equal(y_true,1),np.equal(y_pred,1))) # 正向、正确
TN = np.sum(np.logical_and(np.equal(y_true,0),np.equal(y_pred,0))) # 负向、正确
FP = np.sum(np.logical_and(np.equal(y_true,0),np.equal(y_pred,1))) # 正向、错误
FN = np.sum(np.logical_and(np.equal(y_true,1),np.equal(y_pred,0))) # 负向、错误

Accuracy = (TP+TN)/(TP+FP+TN+FN)
precision = TP/(TP+FP)
recall = TP/(TP+FN)
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