Solve (Network Analyst)—ArcMap

Summary
Usage
Syntax
Code sample
Environments
Licensing information

Summary

Solves the network analysis layer problem based on its network locations and properties.

Usage

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 tool will consume credits when the network analysis layer references ArcGIS Online as the network data source. For more information, see Service Credits Overview.

Syntax

arcpy.na.Solve(in_network_analysis_layer, {ignore_invalids}, {terminate_on_solve_error}, {simplification_tolerance}, {overrides})

Parameter	Explanation	Data Type
in_network_analysis_layer	The network analysis layer on which the analysis will be computed.	Network Analyst Layer
ignore_invalids (Optional)	Specifies whether invalid input locations will be ignored. SKIP —The solver will skip over network locations that are unlocated and solve the analysis layer from valid network locations only. It will also continue solving if locations are on nontraversable elements or have other errors. This is useful if you know your network locations are not all correct, but you want to solve with the network locations that are valid. This is the default. HALT —Do not solve if there are invalid locations. You can then correct these and rerun the analysis.	Boolean
terminate_on_solve_error (Optional)	Specifies whether tool execution should terminate if an error is encountered during the solve. TERMINATE —The tool will fail to execute when the solver encounters an error. This is the default. When you use this option, the Result object is not created when the tool fails to execute due to a solver error. You should obtain the geoprocessing messages from the ArcPy object. CONTINUE —The tool will not fail and continue execution even when the solver encounters an error. All of the error messages returned by the solver will be converted to warning messages. When you use this option, the Result object is always created and the maxSeverity property of the Result object is set to 1 even when the solver encounters an error. Use the getOutput method of the Result object with an index value of 1 to determine if the solve was successful.	Boolean
simplification_tolerance (Optional)	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.	Linear Unit
overrides (Optional)	Specify additional settings that can influence the behavior of the solver when finding solutions for the network analysis problems. The value for this parameter needs to be specified in JavaScript Object Notation (JSON). For example, a valid value is of the following form {"overrideSetting1" : "value1", "overrideSetting2" : "value2"}. The override setting name is always enclosed in double quotation marks. The values can be either a number, Boolean, or a string. The default value for this parameter is no value, which indicates not to override any solver settings. Overrides are advanced settings that should be used only after careful analysis of the results obtained before and after applying the settings. A list of supported override settings for each solver and their acceptable values can be obtained by contacting Esri Technical Support.	String

Derived Output

Name	Explanation	Data Type
output_layer	The solved network analysis layer.	Network Analyst Layer
solve_succeeded	A Boolean indicating whether or not solve succeeded.	Boolean

Code sample

Solve example 1 (Python window)

Execute the tool using all the parameters.

arcpy.na.Solve("Route", "HALT", "TERMINATE", "10 Meters")

Solve example 2 (workflow)

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()[2]
    print "An error occurred on line %i" % tb.tb_lineno
    print str(e)

Environments

Current Workspace

Licensing information

Basic: Requires Network Analyst
Standard: Requires Network Analyst
Advanced: Requires Network Analyst