python预测模型效果评估_python机器学习库sklearn——模型评估

python机器学习库sklearn——模型评估

发布时间：2018-04-07 12:34,

浏览次数：981

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python

sklearn

全栈工程师开发手册 (作者：栾鹏)

python数据挖掘系列教程

各类模型评估详细意思参考：https://blog.csdn.net/luanpeng825485697/article/details/79419353

常见场景: 预定义值

Scoring(得分) Function(函数) Comment(注解)

Classification(分类)

‘accuracy’ metrics.accuracy_score

‘average_precision’ metrics.average_precision_score

‘f1’ metrics.f1_score for binary targets(用于二进制目标)

‘f1_micro’ metrics.f1_score micro-averaged(微平均)

‘f1_macro’ metrics.f1_score macro-averaged(微平均)

‘f1_weighted’ metrics.f1_score weighted average(加权平均)

‘f1_samples’ metrics.f1_score by multilabel sample(通过 multilabel 样本)

‘neg_log_loss’ metrics.log_loss requires predict_proba support(需要

predict_proba 支持)

‘precision’ etc. metrics.precision_score suffixes apply as with ‘f1’(后缀适用于

‘f1’)

‘recall’ etc. metrics.recall_score suffixes apply as with ‘f1’(后缀适用于 ‘f1’)

‘roc_auc’ metrics.roc_auc_score

Clustering(聚类)

‘adjusted_mutual_info_score’ metrics.adjusted_mutual_info_score

‘adjusted_rand_score’ metrics.adjusted_rand_score

‘completeness_score’ metrics.completeness_score

‘fowlkes_mallows_score’ metrics.fowlkes_mallows_score

‘homogeneity_score’ metrics.homogeneity_score

‘mutual_info_score’ metrics.mutual_info_score

‘normalized_mutual_info_score’ metrics.normalized_mutual_info_score

‘v_measure_score’ metrics.v_measure_score

Regression(回归)

‘explained_variance’ metrics.explained_variance_score

‘neg_mean_absolute_error’ metrics.mean_absolute_error

‘neg_mean_squared_error’ metrics.mean_squared_error

‘neg_mean_squared_log_error’ metrics.mean_squared_log_error

‘neg_median_absolute_error’ metrics.median_absolute_error

‘r2’ metrics.r2_score from sklearn import svm, datasets from

sklearn.model_selectionimport cross_val_score,cross_validate # 交叉验证中的模型度量 import

numpyas np # 快速操作结构数组的工具 import matplotlib.pyplot as plt # 可视化绘制 from

sklearn.linear_modelimport LinearRegression # 线性回归 from sklearn.metrics import

make_scorerfrom sklearn import metrics #

=============================分类度量=============================== print(

'=============================分类度量===============================') iris =

datasets.load_iris()# 加载iris 数据集；用于分类问题 X, y = iris.data, iris.target #

150个样本，4个属性，3种分类 clf = svm.SVC(probability=True, random_state=0) #

===========================交叉验证获取度量======================= score =

cross_val_score(clf, X, y, scoring='accuracy',cv=3) # 默认进行三次交叉验证 print('交叉验证度量：'

,score)# ===========================自定义度量======================= #

自定义度量函数，输入为真实值和预测值 def my_custom_loss_func(ground_truth, predictions): diff =

np.abs(ground_truth - predictions).max()return np.log(1 + diff) loss =

make_scorer(my_custom_loss_func, greater_is_better=False) #

自定义度量对象。结果越小越好。greater_is_better设置为false，系统认为是损失函数，则会将计分函数取反 score =

make_scorer(my_custom_loss_func, greater_is_better=True) # 自定义度量对象。结果越大越好 clf =

svm.SVC() clf.fit(X, y) print(loss(clf,X,y))#

对模型进行度量，系统会自动调用模型对输入进行预测，并和真实输出值进行比较，计算损失函数 print(score(clf,X,y)) #

对模型进行度量，系统会自动调用模型对输入进行预测，并和真实输出值进行比较，计算得分 #

============================多种度量值========================= scoring = [

'precision_macro', 'recall_macro'] # precision_macro为精度，recall_macro为召回率 scores

= cross_validate(clf, X, y,scoring=scoring,cv=5, return_train_score=True)

sorted(scores.keys()) print('多种度量的测试结果：',scores) # scores类型为字典。包含训练得分，拟合次数，

score-times (得分次数) # ============================分类指标=========================

clf = svm.SVC()# 构建模型 clf.fit(X, y) # 训练模型 predict_y = clf.predict(X) # 预测数据

print('准确率指标：',metrics.accuracy_score(y, predict_y)) # 计算准确率 print('Kappa指标：'

,metrics.cohen_kappa_score(y, predict_y))# Kappa 检验 print('混淆矩阵：\n'

,metrics.confusion_matrix(y, predict_y))# 混淆矩阵 target_names = ['class 0',

'class 1', 'class 2'] print('分类报告：\n',metrics.classification_report(y,

predict_y, target_names=target_names))# 分类报告 print('汉明损失：'

,metrics.hamming_loss(y, predict_y))#汉明损失 。在多分类中， 汉明损失对应于 y 和 predict_y 之间的汉明距离

print('Jaccard 相似系数：',metrics.jaccard_similarity_score(y, predict_y)) # Jaccard

相似系数 # 下面的系数在在二分类中不需要使用average参数，在多分类中需要使用average参数进行多个二分类的平均 #

average可取值：macro(宏)、weighted(加权)、micro(微)、samples(样本)、None(返回每个类的分数) print(

'精度计算：',metrics.precision_score(y, predict_y, average='macro')) print('召回率：'

,metrics.recall_score(y, predict_y,average='micro')) print('F1值：'

,metrics.f1_score(y, predict_y,average='weighted')) print('FB值：'

,metrics.fbeta_score(y, predict_y,average='macro', beta=0.5)) print('FB值：'

,metrics.fbeta_score(y, predict_y,average='macro', beta=1)) print('FB值：'

,metrics.fbeta_score(y, predict_y,average='macro', beta=2)) print('精确召回曲线：'

,metrics.precision_recall_fscore_support(y, predict_y,beta=0.5,average=None))

print('零一损失：',metrics.zero_one_loss(y, predict_y)) # ROC曲线(二分类) y1 = np.array([0

,0, 1, 1]) # 样本类标号 y_scores = np.array([0.1, 0.4, 0.35, 0.8]) #

样本的得分(属于正样本的概率估计、或置信度值) fpr, tpr, thresholds = metrics.roc_curve(y1, y_scores,

pos_label=1) print('假正率：',fpr) print('真正率：',tpr) print('门限：',thresholds) print(

'AUC值：',metrics.roc_auc_score(y1, y_scores)) labels = np.array([0, 1, 2]) #

三种分类的类标号 pred_decision = clf.decision_function(X) #

计算样本属于每种分类的得分，所以pred_decision是一个3列的矩阵 print('hinge_loss：',metrics.hinge_loss(y,

pred_decision, labels = labels))# 逻辑回归损失，对真实分类和预测分类概率进行对比的损失 y_true = [0, 0, 1,

1] y_pred = [[.9, .1], [.8, .2], [.3, .7], [.01, .99]] print('log_loss：'

,metrics.log_loss(y_true, y_pred))#

===============================回归度量============================== print('

===============================回归度量==============================') diabetes =

datasets.load_diabetes()# 加载糖尿病数据集；用于回归问题 X, y = diabetes.data, diabetes.target

# 442个样本，10个属性，数值输出 model = LinearRegression(copy_X=True, fit_intercept=True,

n_jobs=1, normalize=False) model.fit(X, y) # 线性回归建模 predicted_y =

model.predict(X)# 使用模型预测 print('解释方差得分：',metrics.explained_variance_score(y,

predicted_y))# 解释方差得分 print('平均绝对误差：',metrics.mean_absolute_error(y,

predicted_y))# 平均绝对误差 print('均方误差：',metrics.mean_squared_error(y, predicted_y))

# 均方误差 print('均方误差对数：',metrics.mean_squared_log_error(y, predicted_y)) # 均方误差对数

print('中位绝对误差：',metrics.median_absolute_error(y, predicted_y)) # 中位绝对误差 print(

'可决系数：',metrics.r2_score(y, predicted_y, multioutput='variance_weighted')) #可决系数

print('可决系数：',metrics.r2_score(y, predicted_y, multioutput='raw_values')) #可决系数

print('可决系数：',metrics.r2_score(y, predicted_y, multioutput='uniform_average'))

#可决系数