地理信息系統(tǒng)GIS課件11

Chapter11DataExploration1CHAPTER11

DATAEXPLORATIONBeginningofGISanalysisWhatdoyoudowithadatabaseofdozensoflayersandhundredsofattributes?Dataexplorationallowsyoutoexaminetrends,focusonrelationshipsBetterunderstanddataLinkmaps,graphs,andtables211.1DataExplorationExploratorydataanalysisStatisticalanalysisDynamicgraphicsDatavisualizationFindingGestalt(findingpatternsandpropertiesinadataset)PosingqueriesMakingcomparisons311.1.1DescriptiveStatisticsSummarizevaluesofadatasetRangeMedianMeanModeQuantileanalysisVarianceStandarddeviationZscoreGISpackagesofferdescriptivestatistics411.1.2GraphsVisualdisplayofdataNumerouspossibilities5Figure11.1Alinegraph.6Figure11.2Ahistogram.7Figure11.4Ascatterplotplotting%persons18yearsoldin2000against%populationchange,1990–2000.Aweakpositiverelationship,withacorrelationcoefficientof0.376,ispresentbetweenthetwovariables.8Figure11.5Abubbleplotshowing%populationchange,1990–2000,alongthex-axis;%personsunder18yearsoldin2000alongthey-axis;andstatepopulationin2000bythebubblesize.9Figure11.6Aboxplotbasedonthe%populationchange,1990–2000,dataset.10Figure11.8AQQplotplotting%populationchange,1990-2000datavalueagainstthestandardizedvaluefromanormaldistribution.11Figure11.9A3-Dplotshowingannualprecipitationat105weatherstationsinIdaho.Anorthtosouthdecreasingtrendisapparentintheplot.1211.1.3DynamicGraphicsGraphsdisplayedinmultipleanddynamicallylinkedwindowsDirectlymanipulatedatapointsPosequeryinonewindowandgetresponseinanotherwindowMultiplelinkedwindowsoptimalframeworkforposingqueries13BrushingFigure11.10Thescatterplotontheleftisdynamicallylinkedtothemapontheright.The“brushing”oftwodatapointsinthescatterplothighlightsthecorrespondingstates(WashingtonandNewMexico)onthemap.1411.1.4DataExplorationandGISSimilartoexploratorydataanalysisinstatistics,withtwodifferencesInGISitinvolvesbothspatialandattributedataMediafordataexplorationinGISinvolvesmapsandmapfeatures1511.2AttributeDataQuerySearchattributedatainordertoretrieveadatasubsetSelectedsubsetcanbeexaminedinatable,displayedincharts,orlinkedtomapfeaturesExpressionswhichmustbeinterpretablebytheGIS1611.2.1SQL(StructuredQueryLanguage)DataquerylanguagedesignedforrelationaldatabasesDesignedbyIBMinthe1970sandusedbymanycommercialdatabasemanagementsystems17SQLStructure(Syntax)select<attributelist>from<relation>where<condition>selectkeywordselectsfieldsfromselectstableswherespecifiestheconditionorcriterionfordataquery18Figure11.11PINrelatestheownerandparceltablesandallowsuseofSQLwithbothtables.19SQLExamplesQueriessaledateofparcelcodedP101selectParcel.Sale_datefromParcelwhereParcel.PIN=‘P101’20SQLExamplesQueriesparcelslargerthan2acresthatarezonedcommercialselectParcel.PINfromParcelwhereParcel.Acres>2ANDParcel.Zone_code=221SQLExamplesQueriessaledateofparcelownedbyCostelloselectParcel.Sale_datefromParcel,OwnerwhereParcel.PIN=Owner.PINANDOwner_name=‘Costello’Thisqueryinvolvestwotableswhichmustbejoinedfirst22Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.11.2.2QueryExpressionswhereexpressioncontainsBooleanexpressionsandBooleanconnectors23Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.BooleanExpressionsContainstwooperandsandalogicaloperatorParcel.PIN=‘P101’Operatorsinclude=,<,>,>=,<=,<>24Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.BooleanConnectorsAND,OR,XOR,NOTUsedtoconnecttwoormoreexpressions25Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.Figure11.12TheshadedportionrepresentsthecomplementofdatasubsetA(top),theunionofdatasubsetsAandB(middle),andtheintersectionofAandB(bottom).26Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.11.2.3TypeofOperationSelectasubsetanddividethedataintotwogroupsThosecontainingtheselectedrecordsThosecontainingtheunselectedrecordsThreetypesofoperationsAddmorerecordsSubtractrecordsSelectsmallersubset27Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.Figure11.13Threetypesofoperationmaybeperformedonthesubsetof40records:addmorerecordstothesubset(+2),removerecordsfromthesubset(-5),orselectasmallersubset(20).28Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.11.2.4ExamplesofQueryOperationsSelectadatasubsetandaddmorerecordstoitSelectadatasubsetandswitchselectionSelectadatasubsetandselectasmallersubsetfromit29Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.11.2.5RelationalDatabaseQueryRelationaldatabaseoftenconsistsofmanytables.ArelationaldatabasequeryselectsoverlappingrecordsfromalltablesMustunderstandthestructureofthedatabaseCaneitherjoinorrelatethetables30Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.Figure11.14ThekeysrelatingthreedBASEfilesintheMUIRdatabaseandthesoilattributetable.31Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.11.3SpatialDataQueryRetrievingdatasubsetfromalayerbyworkingdirectlywithfeaturesSelectfeaturesusingcursor,graphic,orspatialrelationshipbetweenfeatures.Resultscanbedisplayedonamap,linkedtorecordsinatable,displayedincharts,orsavedasanewdatasetforfurtherprocessing3211.3.1FeatureSelectionbyCursorPointingandselectingorbydraggingaboxaroundthemapfeatures3311.3.2FeatureSelectionbyGraphicUsesagraphic,suchasacircle,box,lineorpolygontoselectfeaturesthatfallinsideorareintersectedbythegraphicExamples:selectingrestaurantswithinaone-mileradiusofahotel,selectinglandparcelsthatintersectaproposedhighway,orfindingownersoflandparcelswithinaproposednaturereserve34Figure11.15SelectfeaturesbyacirclecenteredatSunValley.3511.3.3FeatureSelectionbySpatialRelationshipSelectfeaturesbasedontheirspatialrelationshiptootherfeaturesInsamelayerorindifferentlayersContainment,intersect,proximity36ContainmentSelectfeaturesthatfallcompletelywithinfeaturesforselectionSchoolswithinaparticularcounty,stateparkswithinaparticularstate37IntersectSelectfeaturesthatintersectotherfeaturesSelectinglandparcelsthatintersectaproposedroad,urbanareasthatintersectafaultline38ProximitySelectfeatureswithinaspecifieddistanceofotherfeaturesStateparkswithintenmilesofaninterstatehighwayAdjacency-whenfeaturestobeselectedandselectionfeaturessharecommonboundary3911.3.4CombiningAttributesandSpatialDataQueriesWhendataexplorationrequiresbothattributeandspatialqueryGasstationswithinonemileoffreewayexitsandhaveanannualrevenueexceeding$2million4011.4RasterDataQueryConceptandsomemethodssameasforvectordataqueryPracticaldifferences4111.4.1QuerybyCellValueOperandisrasteritselfratherthanafield,asinvectorqueryBooleanstatementtoseparatecellsthatsatisfythequerystatementfromthosethatdonot42Figure11.16Rasterdataquery:slope=2andaspect=1.Selectedcellsarecoded1andothers0intheoutputraster.43Copyright?TheMcGrawHillCompanies,Inc.Permissionrequiredforreproductionordisplay.11.4.2QuerybySelectFeaturesQuerybyusingfeaturesuchaspoints,circles,boxes,orpolygons4411.5GeographicVisualizationCartographicvisualizationUsingmapstoprocessvisualinformationData