networkShortestPath

Shortest Path

Calculates the shortest route between a set of points in a pre-defined order along a Bidirectional Network (BDN) using Dijkstra's algorithm. The "shortest" route can refer to different variables (distance, time, etc.) depending what cost was used for building the reference network. The points will be used in their order in the input layer. The order can be changed if the Sort Field parameter is used.

Inputs:

A Network created with ET GeoWizards (.etn file). Must be a Bidirectional Network (BDN)
Input Point layer representing the points to be visited.
Snap tolerance - a distance to the network features. If the points are closer than this distance to a network feature they will be used in the analysis otherwise they will be ignored. The distance is in the linear units of the spatial reference used as a source for creation of the Network.

Input Point Barrier layer. The points of this layer represent barriers. The closest edge to each of these points (if within the snap tolerance) will be considered closed and will not participate in the network analysis.
Direction field for the Input Point Barrier layer. In Bidirectional network the barriers can be set for only one of the directions. This can be indicated if the Barrier Point dataset has a field that indicates in which direction the barrier works.

FT - indicates the Barrier will prohibit movement only in the direction of the polyline. Movement against the direction of the polyline is allowed.
TF - indicates the Barrier will prohibit movement only against the direction of the polyline. Movement in the direction of the polyline is allowed.
Any other values in the Direction field will prohibit movement in both directions

Input Point layer representing the points to be visited.
Sort Field which value define in what order the points are to be used when calculating the route.

Outputs:

A Polyline feature layer with polylines that represent the routes between the points. The polylines will have M values where the M will be 0 for the start point and the total cost for the end point of the route. If for example we have 5 input points, the result will have 4 polylines with costs C1, C2, C3 and C4. The end point of the last polyline in the route will have M = C1 + C2 + C3+ C4. The attribute table of the output will have 6 fields

ET_From - indicates the ID of the start point of this route
ET_To - indicates the ID of the end point of this route
ET_Dist - the distance between the start and end point of the polyline connecting 2 points along the network in the linear units of the spatial reference used as a source for creation of the Network.
ET_Cost - the cost to travel from the start point to the end point of the polyline connecting 2 points in the units of the cost used by the Network (meters, feet, minutes, etc.)
AccumDist - Accumulated distance from the start point of the Route to the end point of the polyline in the linear units of the spatial reference used as a source for creation of the Network.
AccumCost - Accumulated cost from the start point of the Route to the end point of the polyline in the units of the cost used by the Network (meters, feet, minutes, etc.)

Notes :

It is recommended that the input point layer has the same spatial reference as the layer used as a source for the Network.
If the spatial reference of the points and the Network are different, the points will be projected to the spatial reference of the Network.
The result layer will have the spatial reference of the Network.

Example:

Results from the Shortest Path function - Network created with no cost field - length of the street segments used as cost.

Results from the Shortest Path function - Length of the street segments used as cost

Results from the Shortest Path function - Network created Cost = "Minutes" - the results represents the quickest routes.

Results from the Shortest Path function - Network created Cost =

Running Programmatically

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Parameters

Expression	Explanation
Function Name	ShortestPath
<Network to Use>	A String - the full name of the Network file (.etn).
<Input Points>	A String representing the input layer. Must be of Point type.
<output dataset>	A String - the full name of the output layer.
<snap tolerance>	A Double representing the snap tolerance(in the units of the spatial reference of the Network).
{Input Barrier Points}	A String representing the input layer with barrier points. Must be of Point type.
{Barriers Direction Field}	A String representing the name of the field in the Input Barrier Points that will indicate the direction in which the barrier defined by each point work . Must be of String type.
{Sort Field}	A String representing the Name of the field to be used to sort the points of the Input Point layer to establish the sequence in which they will be visited.
{Sort Direction}	A String - the sort direction. Valid values. "ASC" "DESC"

Running the function

ETGWPath used in the table below is the full path to ETGWRun.exe (E.G. "C:\Program Files\ETSpatial Techniques\ETGeo Wizards\ETGWRun.exe")

Language	Syntax
Python	subprocess.call([ETGWPath, "ShortestPath", "Network to Use", "Input Points", "output dataset","snap tolerance", "Input Barrier Points", "Barriers Direction Field", "Sort Field" "Sort Direction"])
.NET using ETGWRun.exe	StartInfo.FileName = ETGWPath StartInfo.Arguments = "ShortestPath" "Network to Use" "Input Points" "output dataset" "snap tolerance" "Input Barrier Points" "Barriers Direction Field" "Sort Field" "Sort Direction"
.NET using ETGWOutX.dll	ShortestPath(Network to Use,Input Points, output dataset, snap tolerance,Input Barrier Points, Barriers Direction Field Sort Field,Sort Direction)
ArcPy	arcpy.ShortestPath(Network to Use,Input Points, output dataset, snap tolerance, Input Barrier Points, Barriers Direction Field, Sort Field, Sort Direction)

Notes:

<> - required parameter
{} - optional parameter
See examples for Python , .NET or ArcPy
The argument separator for StartInfo.Arguments is space. If a string might contain a space, you need to double quote it.

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