Adjacency matrix for network facitlities

AndresSevtsuk

Hi all,

I need to to generate an adjacency matrix for a set of facilities on a network. Then output should be a table where you have the facility ID in the first column, its immediate neighboring facilities in the second column, and the distance between them in the third. For example:

1, 2, 24.06
1, 3, 96.33
2, 1, 24.06
3, 1, 148.79
etc.

There is a forum thread on a similar issue from 2008 that resolved the adjacency matrix for the nodes of the network (VB code below). I basically need to do the same thing, except for facilities on the network, not nodes. Is there some ArcObject, similar to 'network forward star', that would get to adjacencies between network facilities? I would ideally like to do this in Python, but VB ok if not feasible. All help appreciated, thanks,
Andres

Public Sub List_Adjacent_Junctions()
On Error GoTo eh

  Dim pMxDoc As IMxDocument
  Set pMxDoc = ThisDocument
 
  Dim pNLayer As INetworkLayer
  Set pNLayer = pMxDoc.FocusMap.Layer(0)
 
  Dim pND As INetworkDataset
  Set pND = pNLayer.NetworkDataset
 
  Dim pNQ As INetworkQuery
  Set pNQ = pND
   
  Dim pEnumNE As IEnumNetworkElement
  Set pEnumNE = pNQ.Elements(esriNETJunction)
   
  Dim pNEdge As INetworkEdge
  Set pNEdge = pNQ.CreateNetworkElement(esriNETEdge)
  Dim pNEFromJunc As INetworkJunction
  Set pNEFromJunc = pNQ.CreateNetworkElement(esriNETJunction)
  Dim pNEToJunc As INetworkJunction
  Set pNEToJunc = pNQ.CreateNetworkElement(esriNETJunction)
 
  Dim pNE As INetworkElement
  Set pNE = pEnumNE.Next

  Dim pNEJunc As INetworkJunction
  Set pNEJunc = pNE
  'here start the code to store the output on a text file
  Dim strOutputFile As String
  strOutputFile = "C:\my.txt"
  Open strOutputFile For Output As #1
 
  Dim i As Integer
  Do Until pNE Is Nothing
      For i = 0 To pNEJunc.EdgeCount - 1  'For each connected edge...
      pNEJunc.QueryEdge i, True, pNEdge   'Get that connected edge
      pNEdge.QueryJunctions pNEFromJunc, pNEToJunc  'Get To junction of current edge
      Print #1, pNEFromJunc.EID & ", "; pNEToJunc.EID & ","; pNEdge.AttributeValueByName("Length") 'List the adjacency and the edge's length
    Next
    Set pNE = pEnumNE.Next
  Loop
  Exit Sub
  Close #1
eh:
  MsgBox "Error: " & Err.Description
End Sub

JaySandhu

It will be more efficent if you wrote your own network traversal, simillar to service area but now you are in the realm of graph algorithms and yes, arcobject to access the network forward star. I would not recommend this path as it will take longer to write/debug this approach as opposed to the one day run time of the approach outlined previously.

In any case, the other approaches will still have to solve for each 30,000 origins to determine the adjacenies. There is no additional information that will say which are the adjacent locations without running a search from each origin location.

Jay Sandhu