Summary
Provides access to analysis properties from a closest facility network analysis layer. The GetSolverProperties function is used to obtain a ClosestFacilitySolverProperties object from a closest facility network analysis layer.
Discussion
The ClosestFacilitySolverProperties object provides read and write access to all the analysis properties of a closest facility network analysis layer. The object can be used to modify the desired analysis properties of the closest facility layer, and the corresponding layer can be resolved to determine the appropriate results. A new closest facility layer can be created using the Make Closest Facility Analysis Layer geoprocessing tool. Obtaining the ClosestFacilitySolverProperties object from a new closest facility layer allows you to reuse the existing layer for subsequent analyses rather than create a layer for each analysis, which can be slow.
After modifying the properties on the ClosestFacilitySolverProperties object, the corresponding layer can be immediately used with other functions and geoprocessing tools. There is no refresh or update of the layer required to honor the changes modified through the object.
Properties
| Property | Explanation | Data Type |
| accumulators (Read and Write) | Provides the ability to get or set a list of network cost attributes that are accumulated as part of the analysis. An empty list, [], indicates that no cost attributes are accumulated. | String |
| attributeParameters (Read and Write) | Provides the ability to get or set the parameterized attributes to be used in the analysis. The property returns a Python dictionary. The dictionary key is a two-value tuple consisting of the attribute name and the parameter name. The value for each item in the dictionary is the parameter value. Parameterized network attributes are used to model some dynamic aspect of an attribute's value. For example, a tunnel with a height restriction of 12 feet can be modeled using a parameter. In this case, the vehicle's height in feet should be specified as the parameter value. If the vehicle is taller than 12 feet, this restriction will then evaluate to True, thereby restricting travel through the tunnel. Similarly, a bridge could have a parameter to specify a weight restriction. Attempting to modify the attributeParameters property in place won't result in updated values. Instead, you should always use a new dictionary object to set values for the property. The following two code blocks demonstrate the difference between these two approaches. Do not attempt to modify the attributeParameters property in place; this coding method will not work. Modify the attributeParameters property using a new dictionary object. | Dictionary |
| defaultCutoff (Read and Write) | Provides the ability to get or set the default impedance value at which the solver will stop searching for facilities for a given incident. A value of None is used to specify that no cutoff should be used. | Double |
| defaultTargetFacilityCount (Read and Write) | Provides the ability to get or set the number of closest facilities to find per incident. | Integer |
| ignoreInvalidLocations (Read and Write) | Specifies whether invalid input locations will be ignored. Typically, locations are invalid if they cannot be located on the network. When invalid locations are ignored, the solver will skip them and attempt to perform the analysis using the remaining locations.
| String |
| impedance (Read and Write) | Provides the ability to get or set the network cost attribute used as impedance. This cost attribute is minimized while determining the closest facility and the best route to the closest facility. | String |
| outputPathShape (Read and Write) | Provides the ability to get or set the shape type for the route features that are output by the solver. The following is a list of possible values:
| String |
| restrictions (Read and Write) | Provides the ability to get or set a list of restriction attributes that are applied for the analysis. An empty list, [], indicates that no restriction attributes are used for the analysis. | String |
| solverName (Read Only) | Returns the name of the solver being referenced by the Network Analyst layer used to obtain the solver properties object. The property always returns the string value Closest Facility Solver when accessed from a ClosestFacilitySolverProperties object. | String |
| streetDirectionsProperties (Read and Write) | Provides read and write access to StreetDirectionsProperties, allowing you to customize the directions output from your closest facility layer. | Object |
| timeOfDay (Read and Write) | Provides the ability to get or set the time and date at which the routes should begin or end. The interpretation of this value depends on whether timeOfDayUsage property is set to START_TIME or END_TIME. A value of None can be used to specify that no date and time should be used. Instead of using a particular date, a day of the week can be specified using the following dates.
For example, to specify that the route should start or end at 8:00 a.m. on Monday, specify the value as datetime.datetime(1900, 1, 1, 8,0,0). The timeZoneUsage parameter specifies whether the date and time refer to UTC or the time zone in which the facilities or incidents are located. | DateTime |
| timeOfDayUsage (Read and Write) | Controls whether the value of the timeOfDay property represents the arrival or departure times for the routes. The following is a list of possible values:
| String |
| timeZoneUsage (Read and Write) | Specifies the time zone of the timeOfDay parameter.
Irrespective of the timeZoneUsage setting, if your facilities and incidents are in multiple time zones, the following rules are enforced by the tool:
| String |
| travelDirection (Read and Write) | Provides the ability to get or set the direction of travel between facilities and incidents during the analysis. The following is a list of possible values:
| String |
| useHierarchy (Read and Write) | Controls the use of the hierarchy attribute while performing the analysis. The following is a list of possible values:
| String |
| uTurns (Read and Write) | Provides the ability to get or set the policy that indicates how the U-turns at junctions that could occur during network traversal between stops are being managed by the solver. The following is a list of possible values:
| String |
Method Overview
| Method | Explanation |
| applyTravelMode (travel_mode) | Updates the analysis properties of a network analyst layer based on a travel mode object. The updated network analyst layer can then be solved to complete the analysis. |
Methods
applyTravelMode (travel_mode)
| Parameter | Explanation | Data Type |
travel_mode | A variable that references a travel mode object derived from a network dataset. A list of travel mode objects can be obtained by calling the arcpy.na.GetTravelModes function. | Object |
When a network analyst layer is created, it is assigned default values for all of its analysis properties. The individual analysis properties can be updated using a solver properties object obtained from the network analyst layer. A travel mode stores a predefined set of analysis settings that help to perform a particular analysis, such as a walking time travel mode that stores the analysis settings required to perform a time-based walking analysis.
Using the applyTravelMode method, all the analysis settings that are defined in a travel mode can be applied at once. After the analysis properties are updated, the network analyst layer can be solved to complete the analysis.
If there is an error when updating the solver properties, such as when the provided travel mode references properties that don't exist on the current network dataset or references properties that are no longer applicable to the network dataset that was used to create the network analyst layer corresponding to the solver properties object, no exceptions are raised. The method will execute successfully, but you will get errors when you try to solve such a network analyst layer.
If the travel_mode parameter does not reference a travel mode object or a string, a TypeError exception is raised. If the travel_mode parameter references a string and the string cannot be internally converted to a valid string representation of a travel mode object, a ValueError exception is raised.
Code sample
This script shows how to apply the TruckingTime travel mode to an existing layer.
# Name: ClosestFacilitySolverProperties_ApplyTravelMode.py
# Description: Find the closest rest areas to each weigh station. Use a trucking
# time travel mode to apply truck-related settings to the network
# analysis layer.
# Requirements: Network Analyst Extension
#Import system modules
import arcpy
from arcpy import env
import os
try:
#Check out the Network Analyst extension license
#Set environment settings
output_dir = "C:/Data"
#The NA layer's data will be saved to the workspace specified here
env.workspace = os.path.join(output_dir, "Output.gdb")
env.overwriteOutput = True
#Set local variables
input_gdb = "C:/Data/SanDiego.gdb"
network = os.path.join(input_gdb, "Transportation", "Streets_ND")
facilities = os.path.join(input_gdb, "Analysis", "WeighStations")
incidents = os.path.join(input_gdb, "Analysis", "RestAreaLocations")
layer_name = "ClosestFacility"
#Create a new closest facility analysis layer
make_layer_result = arcpy.na.MakeClosestFacilityLayer(network, layer_name,
"TravelTime")
analysis_layer = make_layer_result.getOutput(0)
#Add facilities and incidents to the analysis layer using default field mappings
sub_layer_names = arcpy.na.GetNAClassNames(analysis_layer)
facility_layer_name = sub_layer_names["Facilities"]
incident_layer_name = sub_layer_names["Incidents"]
arcpy.na.AddLocations(analysis_layer, facility_layer_name, facilities, "#", "#")
arcpy.na.AddLocations(analysis_layer, incident_layer_name, incidents, "#", "#")
#Get the Trucking Time travel mode from the network dataset
travel_modes = arcpy.na.GetTravelModes(network)
trucking_mode = travel_modes["Trucking Time"]
#Apply the travel mode to the analysis layer
solver_properties = arcpy.na.GetSolverProperties(analysis_layer)
solver_properties.applyTravelMode(trucking_mode)
#Solve the analysis layer and save the result as a layer file
arcpy.na.Solve(analysis_layer)
output_layer_file = os.path.join(output_dir, layer_name + ".lyrx")
analysis_layer.saveACopy(output_layer_file)
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 occured on line %i" % tb.tb_lineno)
print(str(e))