NetworkAnalysis

• Engine
• ArcGIS for Desktop Basic
• ArcGIS for Desktop Standard
• ArcGIS for Desktop Advanced
• Server

• NetworkLoader object
• Solver objects
• NetFlag objects
• FlagDisplay objects
• Barrier objects
• Helper objects

NetworkLoader object

Solver objects

• The DisableElementClass method stops traces at every instance of the specified class. For example, if you have a gas pipe that has burst and you need to identify all valves to shut off, you would use this method to set barriers at every valve in the network.
• The ElementBarriers property lets you specify an INetElementBarriers object that contains individual elements to use as barriers. These could be barriers composed of closed street segments, bridges that are out, or individual electric switches that have been opened.
• The SelectionSetBarriers property is similar to the ElementBarriers property. It allows you to specify an ISelectionSetBarriers object to use as a barrier in your trace-solving routine. SelectionSetBarriers are meant to be barriers based on a selected set of elements, such as 8-inch pipes or six-lane highways.

void SetEdgeBarrier(INetwork network, IFeatureClass featClass, int edgeOID1, int
    edgeOID2)
{
    //Create the NetElementBarriers object.
    INetElementBarriersGEN netEdgeBarriers=new NetElementBarriersClass()as
        INetElementBarriersGEN;
    int[] oidArray=new int[2];
    oidArray[0]=edgeOID1;
    oidArray[1]=edgeOID2;
    netEdgeBarriers.Network=network;
    netEdgeBarriers.ElementType=esriETEdge;
    netEdgeBarriers.SetBarriers(featClass.FeatureClassID, oidArray);

    //Set the edge barrier in TraceFlowSolver.
    ITraceFlowSolverGEN traceFlowSolver=new TraceFlowSolverClass()as
        ITraceFlowSolverGEN;
    INetSolver netSolver=traceFlowSolver as INetSolver;
    netSolver.SourceNetwork=network;
    netSolver.ElementBarriers(esriETEdge)=netEdgeBarriers;
}

Sub SetEdgeBarrier(network As INetwork, featClass As IFeatureClass, edgeOID1 As Integer, edgeOID2 As Integer)
    'Create the NetElementBarriers object.
    Dim netEdgeBarriers As INetElementBarriersGEN=New NetElementBarriers
    Dim oidArray(0 To 1) As Integer
    oidArray(0)=edgeOID1
    oidArray(1)=edgeOID2
    netEdgeBarriers.Network=network
    netEdgeBarriers.ElementType=esriETEdge
    netEdgeBarriers.SetBarriers(featClass.FeatureClassID, oidArray)
    
    'Set the edge barrier in TraceFlowSolver.
    Dim traceFlowSolver As ITraceFlowSolverGEN=New TraceFlowSolver
    Dim netSolver As INetSolver=CType(traceFlowSolver, INetSolver)
    netSolver.SourceNetwork=network
    netSolver.ElementBarriers(esriETEdge)=netEdgeBarriers
End Sub

void SetFilterWeights(INetwork network)
{
    int[] range=new int[1];

    //Establish the trace flow solver.
    ITraceFlowSolverGEN traceFlowSolver=new TraceFlowSolverClass()as
        ITraceFlowSolverGEN;
    INetSolver netSolver=traceFlowSolver as INetSolver;
    netSolver.SourceNetwork=network;

    //Add the weights.
    INetSchema netSchema=network as INetSchema;
    INetSolverWeightsGEN netSolverWeights=netSolverWeights as INetSolverWeightsGEN;

    INetWeight netWeight=netSchema.WeightByName("Material");
    netSolverWeights.FromToEdgeFilterWeight=netWeight;
    netSolverWeights.ToFromEdgeFilterWeight=netWeight;
    netSolverWeights.SetFilterType(esriETEdge, esriWFRange, true);
    range[0]=1;
    netSolverWeights.SetFilterRanges(esriETEdge, range, range);

    netWeight=netSchema.WeightByName("Fitting_Type");
    netSolverWeights.JunctionFilterWeight=netWeight;
    netSolverWeights.SetFilterType(esriETJunction, esriWFRange, true);
    range[0]=8;
    netSolverWeights.SetFilterRanges(esriETJunction, range, range);
}

Sub SetFilterWeights(network As INetwork)
    Dim range(0) As Integer
    
    'Establish the trace flow solver.
    Dim traceFlowSolver As ITraceFlowSolverGEN=New TraceFlowSolver
    Dim netSolver As INetSolver=CType(traceFlowSolver, INetSolver)
    netSolver.SourceNetwork=network
    
    'Add the weights.
    Dim netSchema As INetSchema=CType(network, INetSchema)
    Dim netSolverWeights As INetSolverWeightsGEN=CType(netSolverWeights, INetSolverWeightsGEN)
    
    Dim netWeight As INetWeight=netSchema.WeightByName("Material")
    netSolverWeights.FromToEdgeFilterWeight=netWeight
    netSolverWeights.ToFromEdgeFilterWeight=netWeight
    netSolverWeights.SetFilterType(esriETEdge, esriWFRange, True)
    range(0)=1
    netSolverWeights.SetFilterRanges(esriETEdge, range, range)
    
    netWeight=netSchema.WeightByName("Fitting_Type")
    netSolverWeights.JunctionFilterWeight=netWeight
    netSolverWeights.SetFilterType(esriETJunction, esriWFRange, True)
    range(0)=8
    netSolverWeights.SetFilterRanges(esriETJunction, range, range)
End Sub

• FindCircuits (sometimes known as find loops) finds elements that can be reached from more than one direction. This method is important for such things as electrical networks, where electricity traveling in both directions on an edge can cause problems.
• FindCommonAncestors finds the common elements in an upstream trace from more than one location. This method helps determine potential pollution sources based on sites where contaminants have been discovered or identify potential outage locations when multiple customers have reported that their service is out.
• FindFlowElements and FindFlowEndElements perform the same type of analysis. The only difference is that FindFlowEndElements returns only the termination elements of the trace. These methods are probably the most important trace methods because they solve problems, such as what is upstream from this location, what is downstream, what is connected, and so on. By applying further constraints (such as disabling classes), these methods can perform additional analysis, such as shutoff modeling.
• FindPath determines the optimal path between two or more flags. The flags are routed in order beginning with the first flag entered and ending with the last. By default, the optimal path is based on the number of elements traversed, with optimal being the least number of elements. Define weights on the network to base the optimal path on length of segments, travel time, or some other parameter.

NetFlag objects

FlagDisplay objects

void FlagDisplay(INetworkAnalysisExtFlags flags, ITraceFlowSolverGEN traceSolver)
{
    IEdgeFlag[] edgeFlags=new IEdgeFlag[flags.EdgeFlagCount];
    IFlagDisplay edgeFlagDisplay;
    INetFlag edgeFlag;
    for (int i=0; i < flags.EdgeFlagCount; i++)
    {
        edgeFlagDisplay=flags.EdgeFlag(i);
        edgeFlag=New EdgeFlagClass()as INetFlag;
        edgeFlag.UserID=edgeFlagDisplay.FID;
        edgeFlag.UserClassID=edgeFlagDisplay.FeatureClassID;
        edgeFlag.Label="Edge";
        edgeFlags[i]=edgeFlag;
    }
    traceSolver.PutEdgeOrigins(edgeFlags);
}

Sub FlagDisplay(flags As INetworkAnalysisExtFlags, traceSolver As ITraceFlowSolverGEN)
    Dim edgeFlags() As IEdgeFlag, edgeFlagDisplay As IFlagDisplay
    Dim edgeFlag As INetFlag, i As Integer
    ReDim edgeFlags(0 To flags.EdgeFlagCount - 1)
    For i=0 To flags.EdgeFlagCount - 1
        edgeFlagDisplay=flags.EdgeFlag(i)
        edgeFlag=New EdgeFlag
        edgeFlag.UserID=edgeFlagDisplay.FID
        edgeFlag.UserClassID=edgeFlagDisplay.FeatureClassID
        edgeFlag.Label="Edge"
        edgeFlags(i)=edgeFlag
    Next i
    traceSolver.PutEdgeOrigins(edgeFlags)
End Sub

Barrier objects

Helper objects

void PlaceJunctionFlag(double x, double y, IMap map, INetworkAnalysisExt
    networkAnalysisExt, ISymbol flagSymbol)
{
    IPoint point=new PointClass()as IPoint;
    point.X=x;
    point.Y=y;
    int EID;
    IPoint outPoint;
    IPointToEID pointToEID=new PointToEIDClass()as IPointToEID;
    pointToEID.GeometricNetwork=networkAnalysisExt.CurrentNetwork;
    pointToEID.SourceMap=map;
    pointToEID.SnapTolerance=10; //Set a snap tolerance of 10 map units.
    pointToEID.GetNearestJunction(point, out EID, out outPoint);

    INetElements netElements=networkAnalysisExt.CurrentNetwork.Network as
        INetElements;
    int FCID, FID, subID;
    pNetElements.QueryIDs(EID, esriETJunction, out FCID, out FID, out subID);
    IJunctionFlagDisplay junctionFlagDisplay=new JunctionFlagDisplayClass()as
        IJunctionFlagDisplay;
    IFlagDisplay flagDisplay=junctionFlagDisplay as IFlagDisplay;
    flagDisplay.FeatureClassID=FCID;
    flagDisplay.FID=FID;
    flagDisplay.SubID=subID;
    flagDisplay.Geometry=outPoint as IGeometry;
    flagDisplay.Symbol=flagSymbol;

    INetworkAnalysisExtFlags networkAnalysisExtFlags=networkAnalysisExt as
        INetworkAnalysisExtFlags;
    networkAnalysisExtFlags.AddJunctionFlag(junctionFlagDisplay);
}

Sub PlaceJunctionFlag(x As Double, y As Double, map As IMap, _
                      networkAnalysisExt As INetworkAnalysisExt, flagSymbol As ISymbol)
    Dim point As IPoint=New Point
    point.X=x
    point.Y=y
    Dim EID As Integer
    Dim outPoint As IPoint
    Dim pointToEID As IPointToEID=New PointToEID
    With pointToEID
        .GeometricNetwork=networkAnalysisExt.CurrentNetwork
        .SourceMap=map
        .SnapTolerance=10 'Set a snap tolerance of 10 map units.
        .GetNearestJunction(point, EID, outPoint)
    End With
    
    Dim netElements As INetElements=CType(networkAnalysisExt.CurrentNetwork.Network, INetElements)
    Dim FCID As Integer, FID As Integer, subID As Integer
    pNetElements.QueryIDs(EID, esriETJunction, FCID, FID, subID)
    Dim junctionFlagDisplay As IJunctionFlagDisplay=New JunctionFlagDisplay
    Dim flagDisplay As IFlagDisplay=CType(junctionFlagDisplay, IFlagDisplay)
    With flagDisplay
        .FeatureClassID=FCID
        .FID=FID
        .SubID=subID
        .Geometry=CType(outPoint, IGeometry)
        .Symbol=flagSymbol
    End With
    Dim networkAnalysisExtFlags As INetworkAnalysisExtFlags=CType(networkAnalysisExt, INetworkAnalysisExtFlags)
    networkAnalysisExtFlags.AddJunctionFlag(junctionFlagDisplay)
End Sub