用python绘制ROC曲线进行多分类
从这里跟进: 我想为我46个班的每个班画ROC曲线。我有300个测试样本,我已经运行了我的分类器来进行预测用python绘制ROC曲线进行多分类,python,numpy,scikit-learn,roc,Python,Numpy,Scikit Learn,Roc,从这里跟进: 我想为我46个班的每个班画ROC曲线。我有300个测试样本,我已经运行了我的分类器来进行预测 y_test是真正的类,而y_pred是我的分类器预测的 这是我的密码: from sklearn.metrics import confusion_matrix, roc_curve, auc from sklearn.preprocessing import label_binarize import numpy as np y_test_bi = l
y_test
是真正的类,而y_pred
是我的分类器预测的
这是我的密码:
from sklearn.metrics import confusion_matrix, roc_curve, auc
from sklearn.preprocessing import label_binarize
import numpy as np
y_test_bi = label_binarize(y_test, classes=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18, 19,20,21,2,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,3,40,41,42,43,44,45])
y_pred_bi = label_binarize(y_pred, classes=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18, 19,20,21,2,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,3,40,41,42,43,44,45])
# Compute ROC curve and ROC area for each class
fpr = dict()
tpr = dict()
roc_auc = dict()
for i in range(2):
fpr[i], tpr[i], _ = roc_curve(y_test_bi, y_pred_bi)
roc_auc[i] = auc(fpr[i], tpr[i])
但是,现在我得到了以下错误:
Traceback (most recent call last):
File "C:\Users\app\Documents\Python Scripts\gbc_classifier_test.py", line 152, in <module>
fpr[i], tpr[i], _ = roc_curve(y_test_bi, y_pred_bi)
File "C:\Users\app\Anaconda\lib\site-packages\sklearn\metrics\metrics.py", line 672, in roc_curve
fps, tps, thresholds = _binary_clf_curve(y_true, y_score, pos_label)
File "C:\Users\app\Anaconda\lib\site-packages\sklearn\metrics\metrics.py", line 505, in _binary_clf_curve
y_true = column_or_1d(y_true)
File "C:\Users\app\Anaconda\lib\site-packages\sklearn\utils\validation.py", line 265, in column_or_1d
raise ValueError("bad input shape {0}".format(shape))
ValueError: bad input shape (300L, 46L)
回溯(最近一次呼叫最后一次):
文件“C:\Users\app\Documents\Python Scripts\gbc\u classifier\u test.py”,第152行,在
fpr[i]、tpr[i]、u=roc_曲线(y_检验,y_预测)
文件“C:\Users\app\Anaconda\lib\site packages\sklearn\metrics\metrics.py”,第672行,在roc\U曲线中
fps、tps、阈值=\二进制\ clf\曲线(y\真、y\分数、位置标签)
文件“C:\Users\app\Anaconda\lib\site packages\sklearn\metrics\metrics.py”,第505行,在二进制clf曲线中
y_真=列或1d(y_真)
文件“C:\Users\app\Anaconda\lib\site packages\sklearn\utils\validation.py”,第265行,在列\u或\u 1d中
raise VALUERROR(“错误的输入形状{0}”。格式(形状))
ValueError:输入形状错误(300L、46L)
roc\u曲线
采用形状参数[n\u样本]
(),并且您的输入(无论是y\u测试/u bi
还是y\u预测/u bi
)都是形状(300,46)
。注意第一点
我认为问题在于y\u pred\u bi
是一个概率数组,通过调用clf.predict\u proba(X)
(请确认)。由于您的分类器在所有46个类上都进行了训练,因此它为每个数据点输出46维向量,label\u binarize
对此无能为力
我知道两种解决方法:
clf.fit()
之前调用label\u binarize
训练46个binary分类器,然后计算ROC曲线roc\u曲线
。这是我的首选方法,我假设y\u pred\u bi
包含概率使用
标签\u二值化:
import matplotlib.pyplot as plt
from sklearn import svm, datasets
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import label_binarize
from sklearn.metrics import roc_curve, auc
from sklearn.multiclass import OneVsRestClassifier
iris = datasets.load_iris()
X = iris.data
y = iris.target
# Binarize the output
y = label_binarize(y, classes=[0, 1, 2])
n_classes = y.shape[1]
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=.5, random_state=0)
classifier = OneVsRestClassifier(svm.SVC(kernel='linear', probability=True,
random_state=0))
y_score = classifier.fit(X_train, y_train).decision_function(X_test)
fpr = dict()
tpr = dict()
roc_auc = dict()
for i in range(n_classes):
fpr[i], tpr[i], _ = roc_curve(y_test[:, i], y_score[:, i])
roc_auc[i] = auc(fpr[i], tpr[i])
colors = cycle(['blue', 'red', 'green'])
for i, color in zip(range(n_classes), colors):
plt.plot(fpr[i], tpr[i], color=color, lw=lw,
label='ROC curve of class {0} (area = {1:0.2f})'
''.format(i, roc_auc[i]))
plt.plot([0, 1], [0, 1], 'k--', lw=lw)
plt.xlim([-0.05, 1.0])
plt.ylim([0.0, 1.05])
plt.xlabel('False Positive Rate')
plt.ylabel('True Positive Rate')
plt.title('Receiver operating characteristic for multi-class data')
plt.legend(loc="lower right")
plt.show()
感谢您在n_样品上的ip!我忘了做:fpr[I]、tpr[I]、roc\u曲线(y\u test[:,I]、y\u score[:,I])
而是直接通过y\u test
和y\u score
到roc\u曲线
函数。我也有同样的问题。我有y_测试作为形状(648,)和y_probs作为(648,2)。我得到以下错误:ValueError:bad input shape(648,2)如何使y_probs成为一维向量?