数据挖掘导论第4课数据分类和预测

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1、第4课数据分类和预测徐从富，副教授浙江大学人工智能研究所浙江大学本科生《数据挖掘导论》课件内容提纲Whatisclassification?Whatisprediction?IssuesregardingclassificationandpredictionClassificationbydecisiontreeinductionBayesianClassificationPredictionSummaryReferenceClassificationpredictscategoricalclassl

2、abels(discreteornominal)classifiesdata(constructsamodel)basedonthetrainingsetandthevalues(classlabels)inaclassifyingattributeandusesitinclassifyingnewdataPredictionmodelscontinuous-valuedfunctions,i.e.,predictsunknownormissingvaluesTypicalapplicationsCr

3、editapprovalTargetmarketingMedicaldiagnosisFrauddetectionClassificationvs.PredictionClassification—ATwo-StepProcessModelconstruction:describingasetofpredeterminedclassesEachtuple/sampleisassumedtobelongtoapredefinedclass,asdeterminedbytheclasslabelattri

4、buteThesetoftuplesusedformodelconstructionistrainingsetThemodelisrepresentedasclassificationrules,decisiontrees,ormathematicalformulaeModelusage:forclassifyingfutureorunknownobjectsEstimateaccuracyofthemodelTheknownlabeloftestsampleiscomparedwiththeclas

5、sifiedresultfromthemodelAccuracyrateisthepercentageoftestsetsamplesthatarecorrectlyclassifiedbythemodelTestsetisindependentoftrainingset,otherwiseover-fittingwilloccurIftheaccuracyisacceptable,usethemodeltoclassifydatatupleswhoseclasslabelsarenotknownCl

6、assificationProcess(1):ModelConstructionTrainingDataClassificationAlgorithmsIFrank=‘professor’ORyears>6THENtenured=‘yes’Classifier(Model)ClassificationProcess(2):UsetheModelinPredictionClassifierTestingDataUnseenData(Jeff,Professor,4)Tenured?Supervisedv

7、s.UnsupervisedLearningSupervisedlearning(classification)Supervision:Thetrainingdata(observations,measurements,etc.)areaccompaniedbylabelsindicatingtheclassoftheobservationsNewdataisclassifiedbasedonthetrainingsetUnsupervisedlearning(clustering)Theclassl

8、abelsoftrainingdataisunknownGivenasetofmeasurements,observations,etc.withtheaimofestablishingtheexistenceofclassesorclustersinthedataIssuesRegardingClassificationandPrediction(1):DataPreparationDatacleaningPreprocessdatainorderto