数据挖掘—实用机器学习技术及Java实现原书–英文版《DataMining—PracticalMachineLearningToolsandTechniqueswithJavaImplementations》,新西兰IanH.Witten、EibeFrank著Weka–AnopensourceframeworkfortextanalysisimplementedinJavathatisbeingdevelopedattheUniversityofWaikatoinNewZealand.–http://www.cs.waikato.ac.nz/ml/weka/–http://www.mkp.com/datamining/概念:KDD、ML、OLAP与DMKDD(KnowledgeDiscoveryinDatabase)是一种知识发现的一连串过程。ML(MachineLearning)=KD,不限于Database的数据过程:挖掘-数据模式-表示-验证-预测OLAP(OnlineAnalyticalProcess)是数据库在线分析过程。数据挖掘(dataMining)只是KDD/ML的一个重要组成部分。DM用在产生假设,而OLAP则用于查证假设概念:DM与DBDataPreparation要占Datamining过程70%工作量「Database」+「Datamining」=会说话的数据库概念:DataMining概念:数据挖掘是从大量的数据中,抽取出潜在的、有价值的知识(模型或规则)的过程–KeyCharacteristicsofDataMining:•Largeamountofdata•Discoveringpreviouslyunknown,hiddeninformation•Extractingvaluableinformation•MakingimportantbusinessdecisionusingtheinformationDM/ML的一些要点–Thedataisstoredelectronicallyandthesearchisautomatedbycomputer;–Aboutsolvingproblemsbyanalyzingdataalreadypresentindatabases;–Definedastheprocessofdiscoveringpatternsindata;–Thisbookisabout——Techniquesforfindinganddescribingstructuralpatternsindata.–structuralpatterns表示法:表、树、规则概念:MachineLearningTolearn:–togetknowledgeofstudy,experience,orbeingtaught;–tobecomeawarebyinformationorfromobservation;–tocommittomemory;–tobeinformedof,ascertain(确定);toreceiveinstructionShortcomingswhenitcomestotalkingaboutcomputes–It’svirtuallyimpossibletotestiflearningasbeanachievedornot.–Thistieslearningtoperformanceratherthanknowledge简单例子:天气问题*天气数据:weather.nominal.arff运行Weka,载入数据,选择算法id3预测(决策树)•outlook=rainy•|windy=TRUE:no•|windy=FALSE:yes测试方法:采用10Cross-validation的测试结果:ConfusionMatrix(P.138)和准确率•ab<--classifiedas•81|a=yes•14|b=no•CorrectlyClassifiedInstances1285.7143%•IncorrectlyClassifiedInstances214.2857%其他算法:NeuralNetwork数据挖掘的过程步骤:见『回顾:DM的步骤』输入:Concepts,Instances,AttributesConcept–四种基本的学习类型•Classification,association,clustering,numericprediction–不考虑类型,我们把要学习的称为Concept,而把学习的输出成为conceptdescriptionInstance:数据样本记录Attribute:数据字段–Nominal:outlook:sunny=>no–Ordinal:距离无法度量,如hot>mild>cool–Interval:距离可度量,如整数–Ratio:如58.1%输入:Preparingtheinput*Gatheringthedatatogether–Thedatamustbeassembled,integrated,andcleanedup(DataWarehousing)–Selectingtherighttypeandlevelofaggregationisusuallycriticalforsuccess属性类型:•ARFF文件格式(备注:weather.nominal.arff)•支持两种基本类型:nominalandnumeric,尽可能用前者属性值•Missingvalue:去掉该样本、替代、(用?来表示字段值)•Inaccuratevalue:一粒老鼠屎——需要领域知识!Gettingtoknowyourdata!•数据清理一个耗时、费力,却很重要的过程,•Garbagein,garbageout!输出:KnowledgerepresentationDecisiontablesDecisiontreesClassificationrules•IfaandbthenxAssociationrules:多个结果•If…thenoutlook=sunnyandhumidity=highRuleswithexceptions(P.66)•If…then…except…else…except…TreesfornumericpredictionInstance-basedrepresentationClusters算法:ThebasicmethodsSimplicity-first:simpleideas...