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Python sklearn KFold 生成交叉验证数据集的方法

2020-01-04 13:51:36
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源起:

1.我要做交叉验证,需要每个训练集和测试集都保持相同的样本分布比例,直接用sklearn提供的KFold并不能满足这个需求。

2.将生成的交叉验证数据集保存成CSV文件,而不是直接用sklearn训练分类模型。

3.在编码过程中有一的误区需要注意:

这个sklearn官方给出的文档

>>> import numpy as np>>> from sklearn.model_selection import KFold >>> X = ["a", "b", "c", "d"]>>> kf = KFold(n_splits=2)>>> for train, test in kf.split(X):...  print("%s %s" % (train, test))[2 3] [0 1][0 1] [2 3]

我之前犯的一个错误是将train,test理解成原数据集分割成子数据集之后的子数据集索引。而实际上,它就是原始数据集本身的样本索引。

源码:

# -*- coding:utf-8 -*-# 得到交叉验证数据集,保存成CSV文件# 输入是一个包含正常恶意标签的完整数据集,在读数据的时候分开保存到datasetBenign,datasetMalicious# 分别对两个数据集进行KFold,最后合并保存 from sklearn.model_selection import KFoldimport csv def writeInFile(benignKFTrain, benignKFTest, maliciousKFTrain, maliciousKFTest, i, datasetBenign, datasetMalicious): newTrainFilePath = "E://hadoopExperimentResult//5KFold//AllDataSetIIR10//dataset//ImbalancedAllTraffic-train-%s.csv" % i newTestFilePath = "E://hadoopExperimentResult//5KFold//AllDataSetIIR10//dataset//IImbalancedAllTraffic-test-%s.csv" % i newTrainFile = open(newTrainFilePath, "wb")# wb 为防止空行 newTestFile = open(newTestFilePath, "wb") writerTrain = csv.writer(newTrainFile) writerTest = csv.writer(newTestFile) for index in benignKFTrain:  writerTrain.writerow(datasetBenign[index]) for index in benignKFTest:  writerTest.writerow(datasetBenign[index]) for index in maliciousKFTrain:  writerTrain.writerow(datasetMalicious[index]) for index in maliciousKFTest:  writerTest.writerow(datasetMalicious[index]) newTrainFile.close() newTestFile.close()  def getKFoldDataSet(datasetPath): # CSV读取文件 # 开始从文件中读取全部的数据集 datasetFile = file(datasetPath, 'rb') datasetBenign = [] datasetMalicious = [] readerDataset = csv.reader(datasetFile) for line in readerDataset:  if len(line) > 1:   curLine = []   curLine.append(float(line[0]))   curLine.append(float(line[1]))   curLine.append(float(line[2]))   curLine.append(float(line[3]))   curLine.append(float(line[4]))   curLine.append(float(line[5]))   curLine.append(float(line[6]))   curLine.append(line[7])   if line[7] == "benign":    datasetBenign.append(curLine)   else:    datasetMalicious.append(curLine)  # 交叉验证分割数据集 K = 5 kf = KFold(n_splits=K) benignKFTrain = []; benignKFTest = [] for train,test in kf.split(datasetBenign):  benignKFTrain.append(train)  benignKFTest.append(test) maliciousKFTrain=[]; maliciousKFTest=[] for train,test in kf.split(datasetMalicious):  maliciousKFTrain.append(train)  maliciousKFTest.append(test) for i in range(K):  print "======================== "+ str(i)+ " ========================"  print benignKFTrain[i], benignKFTest[i]  print maliciousKFTrain[i],maliciousKFTest[i]  writeInFile(benignKFTrain[i], benignKFTest[i], maliciousKFTrain[i], maliciousKFTest[i], i, datasetBenign,     datasetMalicious)  datasetFile.close()  if __name__ == "__main__":  getKFoldDataSet(r"E:/hadoopExperimentResult/5KFold/AllDataSetIIR10/dataset/ImbalancedAllTraffic-10.csv")

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