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.
Syntax
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) |
| Boolean |
terminate_on_solve_error (Optional) |
| 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
Licensing information
- Basic: Requires Network Analyst
- Standard: Requires Network Analyst
- Advanced: Requires Network Analyst