Solve (Network Analyst)
Solves the network analysis layer problem based on its network locations and properties.
When the solve fails, the warning and error messages provide useful information about the reasons for the failure.
Be sure to specify all the parameters on the network analysis layer that are necessary to solve the problem before running this tool.
The network analysis layer on which the analysis will be computed.
|Network Analyst Layer|
For vehicle routing problem network analysis layer, use HALT as the parameter value since the vehicle routing problem solver requires all the network locations to be valid.
The tolerance that determines the degree of simplification for the output geometry. If a tolerance is specified, it must be greater than zero. You can choose a preferred unit; the default unit is decimal degrees.
Specifying a simplification tolerance tends to reduce the time it takes to render routes or service areas. The drawback, however, is that simplifying geometry removes vertices, which may lessen the spatial accuracy of the output at larger scales.
Because a line with only two vertices cannot be simplified any further, this parameter has no effect on drawing times for single-segment output, such as straight-line routes, OD cost matrix lines, and location-allocation lines.
Execute the tool using all the parameters.
arcpy.na.Solve("Route", "HALT", "TERMINATE", "10 Meters")
The following stand-alone Python script demonstrates how the Solve tool can be used to perform a closest facility analysis and save results to a layer file.
# Name: Solve_Workflow.py # Description: Solve a closest facility analysis to find the closest warehouse # from the store locations and save the results to a layer file on # disk. # Requirements: Network Analyst Extension #Import system modules import arcpy from arcpy import env try: #Check out the Network Analyst extension license arcpy.CheckOutExtension("Network") #Set environment settings env.workspace = "C:/data/Paris.gdb" env.overwriteOutput = True #Set local variables inNetworkDataset = "Transportation/ParisMultimodal_ND" outNALayerName = "ClosestWarehouse" impedanceAttribute = "Drivetime" accumulateAttributeName = ["Meters"] inFacilities = "Analysis/Warehouses" inIncidents = "Analysis/Stores" outLayerFile = "C:/data/output" + "/" + outNALayerName + ".lyr" #Create a new closest facility analysis layer. Apart from finding the drive #time to the closest warehouse, we also want to find the total distance. So #we will accumulate the "Meters" impedance attribute. outNALayer = arcpy.na.MakeClosestFacilityLayer(inNetworkDataset,outNALayerName, impedanceAttribute,"TRAVEL_TO", "",1, accumulateAttributeName, "NO_UTURNS") #Get the layer object from the result object. The closest facility layer can #now be referenced using the layer object. outNALayer = outNALayer.getOutput(0) #Get the names of all the sublayers within the closest facility layer. subLayerNames = arcpy.na.GetNAClassNames(outNALayer) #Stores the layer names that we will use later facilitiesLayerName = subLayerNames["Facilities"] incidentsLayerName = subLayerNames["Incidents"] #Load the warehouses as Facilities using the default field mappings and #search tolerance arcpy.na.AddLocations(outNALayer, facilitiesLayerName, inFacilities, "", "") #Load the Stores as Incidents. Map the Name property from the NOM field #using field mappings fieldMappings = arcpy.na.NAClassFieldMappings(outNALayer, incidentsLayerName) fieldMappings["Name"].mappedFieldName = "NOM" arcpy.na.AddLocations(outNALayer, incidentsLayerName, inIncidents, fieldMappings,"") #Solve the closest facility layer arcpy.na.Solve(outNALayer) #Save the solved closest facility layer as a layer file on disk with #relative paths arcpy.management.SaveToLayerFile(outNALayer,outLayerFile,"RELATIVE") print "Script completed successfully" except Exception as e: # If an error occurred, print line number and error message import traceback, sys tb = sys.exc_info() print "An error occured on line %i" % tb.tb_lineno print str(e)