edu bittorfarunleonnchrisreczhangcswiscedu University of Michigan Ann Arbor University of Wisconsin Madison ABSTRACT A new generation of data processing systems including web search Googles Knowledge Graph IBMs Watson and sev eral di64256erent recomm ID: 39706
Download Pdf The PPT/PDF document "Brainwash A Data System for Feature Engi..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Teamsthathaditbasicallywrong|butforafewgoodideas|madethedi erencewhencombinedwithteamswhichhaditbasicallyright...Thetoptwoteamsbeatthechallengebycombiningteamsandtheiralgorithmsintomorecomplexalgorithmsincorporatingeverybody'swork.Themorepeoplejoined,themoretheresultingteam'sscorewouldincrease.Unfortunately,writingfeaturescanbeextremelypainful.Onthesurface,buildingafeaturemayseemtobejustan-othersoftwareengineeringtask,albeitonethatisrunoververylargedatasets.However,inourexperienceengineer-ingfeaturesrequiresdramaticallymoreiterationandad-justment.Acompletedfeatureisoftenasmallpieceofcodethatisrelativelyeasytoreproduceanddoesnotre ectthelargeamountofcodethatwaswritten,tested,andthrownaway.Wenotethreewaysinwhichfeatureengineeringisuniquelyexcruciating:1.Grunt-WorkStatistics.First,thereisalotofsta-tistical\gruntwork."Afeatureprocessesalargedataset|e.g.,thesetofallwebpagetitles|whosecharac-teristicsareoftenwhollynoveltothedeveloper.Evensimplefeaturesarehardtowritewithoutsomecom-moditymetadata,suchasfrequencydistributionsofuniquevalues,listsofoutliervalues,andsomesimplevisualizations.Todaythefeaturedeveloperperformsthisgruntworkforeverynewfeature,byhand.2.UnknowableSpecs.Mostinterestingdatasetsarelargeandnoisy,makingtheactualfeaturecode\spec"nearlyunknowablewithoutrepeatedtestingagainstthedataitself.Forexample,itiseasytoinformallydescribeafeaturesuchas,\Asocialmediauser'snameissomewhatindicativeoftheuser'sage."Thatis,auserwiththenameBrittanyisrelativelyunlikelytobeelderlyin2013.Butimplementingthisfeatureentailsimplementingarstversion,thenlearningthatusernamesoftenhavenumbersandadjectivesappendedtoahumanrstname,thenwritingcodetostripo thesesuxes,thentestingthecodeagain.3.UnexpectedFailure.Evenaperfectlyimplementedfeaturecanbeanunexpectedfailure,eitherbecauseitdoesnotcaptureanyusefulinformationorbecauseitsinformationisalreadycapturedbyapreviouslyim-plementedfeature.Forexample,itmaybethatthename-basedmethodaboveishelpfulwhenconsideredalone,butdoesnotaddanypredictivepowerbeyondtext-basedmethods(say,countingthenumberof\lol"sinasocialmediauser'sstatusupdates).Ifthetext-basedmethodhadbeenimplementedrst,thenalltheworktoimplementthenamefeatureiswastede ort.Thesethreeburdensoffeatureengineering|grunt-workstatistics,unknowablespecs,andunexpectedfailure|turnthedeveloper'slifeintoanendlesscycleofsmalliterativecodechangesandtests.Moreover,mostfeaturecoderunsoverhugedatasetsthatrequirescalable\bigdata"systems.Thefewsystemsthatsupporttheuser-denedcodeneces-saryforfeatureengineering(e.g.,MapReduce[2])havegen-erallyemphasizedthroughputoverlatency.Clustersoftwarethusforcesdeveloperstoendurehigh-latencywaits(perhapshoursorevendays)inthe\innerloop"ofthefeaturedevel-opmentcycle.Asaresult,featureengineeringisatime-consuminganddrainingexperience.Weenvisionasystem,brainwash,1todramaticallyim-provetheproductivityoffeatureengineers.Itprovidesper-vasiveprogrammerhintstoaddresstheconstantiterationas-sociatedwithfeaturedevelopment.Incontrasttothehintsprovidedbytoday'sIDEs(whicharederivedfromcodesnip-petsorheaderles),hintsinbrainwasharederivedfromthedataunderinspectionaswellascodewrittenbyotherbrainwashdevelopers.Itisamultiusersystemthathasthreephases:1.InExplore,brainwashspeedsthefeatureengineerthroughgrunt-workstatisticsbyautomaticallypro-vidingcommodityinformationlikefrequencydistri-butionsandautomatically-chosenillustrativesamplesfromthedataset.2.InExtract,brainwashattemptstorecommendafea-turethatisbothlikelytoyieldbenetsandroughlycompatiblewiththedeveloper'scodesofar.brain-washaccomplishesthisbyrepurposingsemi-andun-supervisedmethodsforfeatureinductionasrecom-mendationmethods.3.InEvaluate,brainwashenablestheengineertoeval-uatehowwellorpoorlytheirnewfeaturesperforminthecontextoftheentiretrainedsystem.Thechal-lengeforbrainwashistorunandevaluatefeaturesasquicklyaspossible.Itdoessobyspeculativelyex-ecutingcodeitthinkstheuserwillwanttoruninthefuture;whilefeaturescanbearbitrarypiecesofcode,itispossibletomakeeducatedguessesaboutwhatthecodeactuallydoesevenwithoutdirectlyunderstand-ingthesource.Forexample,twofunctionsthatwerewrittenbythesameuserjustafewminutesapartarelikelytobesmallmodicationsofoneanother.ByincreasingthevelocityofthedeveloperineachphaseoftheExplore-Extract-Evaluateloop,brainwashaimstoimprovedevelopere ectivenessduringfeatureengineering.Inthenextsectionwereviewtwocasestudiesfromourownwork,illustratingproblemswithfeatureengineeringto-dayandshowinghowitcouldbeimproved.InSection3,weproposebrainwashanddescribeitsdesign.2.CASESTUDIESWenowdescribetwofeatureengineeringcasestudiesfromtrainedsystemsbeingbuiltbytheauthorsofthispaper.GeoDeepDiveintegratesscienticdataforgeoscientists.Automanaimstoreproducenationaleconomicstatisticsusingsocialmediaactivity.2.1GeoDeepDiveToday,anindividualgeologisthasamicroviewofgeo-science:shehasaccesstomeasurementsfromatmostahandfuloftheapproximately30,000geographicalunitsinNorthAmerica,usuallydatacollectedinherownandpart-nerlabs.Otherlabs'dataisburiedinthetext,gures,and 1brainwashisareferencetotheartistMr.Brainwash,orMBW,whomass-producesartinthemoldoffamousstreetartistBanksy.Similarily,weproposetomass-producetheartistryrequiredbytoday'strainedsystems. Wetreatfeaturedevelopmentasawork owofdeveloper-writtenfunctionsudf0;udf1;:::;udfN.A\run"iconsistsofapplyingudfitoeachtupleintheinputdataset(e.g.,eachwebpage,eachacademicpaper,oreachTweet).Likethemap()fromMapReduce,audffunctioninvocationtakesasingletuplefromtheinputandyieldszeroormoretuplesthatareplacedintotherun'soutput.4Explicitschemasallowbrainwashtoguesswhattheudfisdoing,evenifthefunctionconsistsentirelyofopaquecompiledcode.Weenvisionbrainwashasacentralizedsystemthatsup-portsmanydevelopersandprojectssimultaneously.Evenifdevelopersdonotexplicitlycollaborate,thesystemstoresandsometimesrepurposesdevelopers'work.brainwashcanthusexploitknowledgeabouttheudfwork ow,thedataset,anddeveloperactivitytoaddresseachofthethreeproblemsencounteredinfeatureengineering.1.Explore:Grunt-WorkStatistics.brainwashcanas-sistwithstatisticscollectionbyleveragingtheformalschemaandprevioususers'udfs.Exploitingschemainformationfortherawinputleshouldbestraightforward:thesystemcanautomaticallyreadtheinput,countingtuplesandeldsasitgoes.Theresultshouldbearoughoverviewsimilartowhatiso eredindataintegrationtoolssuchasGoogleRene.However,thisschemainformationisnotsucientwhenthedeveloperwantstoseestatisticson\derivedobjects"thatcomefromrunningudfsonasubeldoftherawinput,suchasthenamedentitiesembeddedinawebpage.Wecanautomatestatisticsonderivedobjectsbyexamin-ingtheoutputschemasanddatasetsfrompreviousudfsthatshareaninputschemawiththecurrentoneunderdevelop-ment.Forexample,consideradeveloperwhohaswrittenoneudfthattransformsarawinputleofwebpagetuplesintoaseriesofparagraphinstancesandthenwritesaseriesofdi erentudfsthattransformparagraphintoalargerangeofoutputswithdi erentschemaformats.Thebodyofudfsnotonlyprovidesevidencethatparagraphisaninterestingandbroadlyusefulobject,italsoprovidesbrainwashwiththecodenecessarytoproduceparagraph.Further,wedonotneedtolimittheseautomatedstatisticstotheuserwhoactuallywroteparagraph-producingcode:itcanbeusedtohelpanyprogrammerwhoneedstoprocesswebpages.2.Extract:UnknowableSpecs.brainwashshouldpre-emptivelysuggestcodethatwilladdressunknowablespeci-cationproblemsbeforethedeveloperevenencountersthem.Forexample,anydeveloperwhoneedstoprocessrstnamesinsocialmediaislikelytowanttoremoveallthestrangeusernamesuxesdescribedinSection1.Wecandothisbypairingschemamatchingwithcodesuggestion.ImagineauserAwhohaswrittenudfAiwhichextractsusernamesfromTweets,aswellasudfAi+1thatnor-malizestheusernames.NowuserBwritesafunctionudfBjthathasaninputschemasimilartoudfAiandgeneratesout-putthatissimilartothatproducedbyudfBi.brainwashshouldthensuggestthatBrunudfAi+1andcanpresentsam-pleinput/outputpairstoexplainwhy.TheremaybealargenumberofcandidatefunctionsthatBcouldapply|rankingthesewillbeacoretechnicalchal-lenge.Likeotherrankingsystems,udfsuggestionshould 4brainwashalsoallowsaggregation,similartoreduce(),butweomitourdescriptionofthismechanismtosimplifyourexposition.improveasdevelopersusethesystem,providingadditionalevidenceaboutwhichudfsareappropriateinwhichcases.3.Evaluate:UnexpectedFailure.Improvingtheover-allperformanceofthetrainedsystemis,intheend,thefeaturedeveloper'srealgoal.Butmeasuringafeature'srealcontributiontotheend-to-endsystemcanentailtrainingandtestingmanydi erentpermutationsoffeatures,eachstepofwhichmayneedtoprocessahugedataset.Asare-sult,developerssidestepsystem-wideevaluationforfartoolonginthedevelopmentprocess.brainwashencouragesfre-quentandfullevaluationbysavingdataonpreviousfeaturepermutations,andspeculativelytrainingstatisticalsystemsusingfeaturesunderdevelopment.Thesystemautomaticallyformulatescodeaccordingtotheabovethreefeatures,thensendstheresultstotheuser'sIDE.Inmanyoftheabovecases,thesystembothformulatescodeandspeculativelyexecutesitontheuser'sbehalf.Thisspeculativeformulate-and-executecycleiswhatal-lowsbrainwashtonotjustgiveprogrammerhints,butreduceexecutionlatencyaswell.Insomecases,suchastheexplorecomponentabove,brainwashreducesuser-apparentlatencysimplybyremovingtheworkfromtheuser'stodolist|wedotheworkwhenthere'sslacktimeintheback-endprocessingsystem.Inothercases,aswithextract,theuser'scodingtargetisunclear;thesystemtriestoguessit,executestheresultingcode,andhopesthatthee ortwasnotwasted.Eveniftheuser'sgoalisnotpre-dicted,thesystemcanusepreviousiterationsofthecurrentudftodeterminewhichinputtuplesarelikelytoyieldusefuloutputsandprioritizetheseduringprocessing.4.CURRENTSTATUSANDNEXTSTEPSWearebuildinganinitialprototypeofbrainwashbasedonthecodeofGeoDeepDive,Automan,andanearlierweb-scaleprototypecalledDeepDive(http://hazy.cs.wisc.edu/deepdive).Ourplanistorenebrainwashandtheseactiveresearchprojectsinparallel.brainwashraisesseveralresearchquestions.Onethatwehaveexaminedistheecacyofdi erentfeature-engineeringmethods.Earlierthisyear,weperformedtherststudythatcomparestwopopularmethodsusedintheexplore-extract-evaluateloop,distantsupervisionandcrowdsourcing,toex-tractrelationshipsatwebscale[7].Thisstudysparkedourinterestinusingdistantsupervisiontorecommendfeaturesintheexploreandextractphases.Weplantousebrain-washasavehicletocontinuesuchstudies.5.REFERENCES[1]E.V.Buskirk.HowtheNet ixPrizeWasWon.Wired,2009.[2]J.DeanandS.Ghemawat.MapReduce:SimpliedDataProcessingonLargeClusters.InOSDI,pages137{150,2004.[3]D.Ferrucci.AnOverviewoftheDeepQAProject.AIMagazine,2012.[4]A.Y.Halevy,P.Norvig,andF.Pereira.TheUnreasonableE ectivenessofData.IEEEIntelligentSystems,2009.[5]S.Levy.HowGoogle'sAlgorithmRulestheWeb.Wired,2010.[6]https://developers.google.com/protocol-buffers/.[7]C.Zhang,F.Niu,C.Re,andJ.Shavlik.BigDataversustheCrowd:LookingforRelationshipsinAlltheRightPlaces.InACL,2012.