RouteSolverProperties (arcpy.na)
Summary
Provides access to analysis properties from a route network analysis layer. The GetSolverProperties function is used to obtain a RouteSolverProperties object from a route network analysis layer.
Discussion
The RouteSolverProperties object provides read and write access to all the analysis properties of a route network analysis layer. The object can be used to modify the desired analysis properties of the route layer, and the corresponding layer can be re-solved to determine the appropriate results. A new route layer can be created using the Make Route Layer geoprocessing tool. Obtaining the RouteSolverProperties object from a new route layer allows you to reuse the existing layer for subsequent analyses rather than create a new layer for each analysis, which can be slow.
After modifying the properties of the RouteSolverProperties 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. #Don't attempt to modify the attributeParameters property in place.
#This coding method won't work.
solverProps.attributeParameters[('HeightRestriction', 'RestrictionUsage')] = "PROHIBITED"
#Modify the attributeParameters property using a new dictionary object.
#This coding method works.
params = solverProps.attributeParameters
params[('HeightRestriction', 'RestrictionUsage')] = "PROHIBITED"
solverProps.attributeParameters = params
| Dictionary |
findBestSequence (Read and Write) | Controls whether the stops are reordered to find optimal routes. The following is a list of possible values:
| 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 best route. | String |
orderingType (Read and Write) | Controls the ordering of stops when findBestSequence property is set to FIND_BEST_ORDER. The following is a list of possible values:
| 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 analysis layer used to obtain the solver properties object. The property always returns the string value Route Solver when accessed from a RouteSolverProperties object. | String |
timeOfDay (Read and Write) | Provides the ability to get or set the start date and time for the route. Route start time is mostly used to find routes based on the impedance attribute that varies with the time of the day. For example, a start time of 9 AM could be used to find a route that considers the rush-hour traffic. 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 at 5:00 PM on Tuesday, specify the value as datetime.datetime(1900, 1, 2, 17,0,0). | DateTime |
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 handled by the solver. 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 |
useTimeWindows (Read and Write) | Controls if time windows will be used at the stops. The following is a list of possible values:
| String |
Code Sample
The script shows how to update the impedance property to the TravelTime cost attribute, specify Minutes and Meters cost attributes as accumulative attributes, and use the current time as the route start time. It assumes that a route network analysis layer called Route has been created in a new map document based on the tutorial network dataset for San Francisco region.
#Get the route layer object from a layer named "Route" in the table of contents
routeLayer = arcpy.mapping.Layer("Route")
#Get the route solver properties object from the route layer
solverProps = arcpy.na.GetSolverProperties(routeLayer)
#Update the properties for the route layer using the route solver properties object
solverProps.impedance = "TravelTime"
solverProps.accumulators = ["Meters", "Minutes"]
#Only set the time component from the current date time as time of day
solverProps.timeOfDay = datetime.datetime.now().time()
The script shows how to find a shortest (distance) and fastest (travel time) route between a set of stops and save each route as a feature class in a geodatabase. It illustrates how to create only one instance of a route layer and modify the impedance property using the RouteSolverProperties object to achieve the desired results.
import arcpy
#Set up the environment
arcpy.env.overwriteOutput = True
arcpy.CheckOutExtension("network")
#Set up variables
networkDataset = "C:/Data/SanFrancisco.gdb/Transportation/Streets_ND"
stops = "C:/Data/SanFrancisco.gdb/Analysis/Stores"
fastestRoute = "C:/Data/SanFrancisco.gdb/FastestRoute"
shortestRoute = "C:/Data/SanFrancisco.gdb/ShortestRoute"
#Make a new route layer using travel time as impedance to determine fastest route
routeLayer = arcpy.na.MakeRouteLayer(networkDataset, "StoresRoute",
"TravelTime").getOutput(0)
#Get the network analysis class names from the route layer
naClasses = arcpy.na.GetNAClassNames(routeLayer)
#Get the routes sublayer from the route layer
routesSublayer = arcpy.mapping.ListLayers(routeLayer, naClasses["Routes"])[0]
#Load stops
arcpy.na.AddLocations(routeLayer, naClasses["Stops"], stops)
#Solve the route layer
arcpy.na.Solve(routeLayer)
#Copy the route as a feature class
arcpy.management.CopyFeatures(routesSublayer, fastestRoute)
#Get the RouteSolverProperties object from the route layer to modify the
#impedance property of the route layer.
solverProps = arcpy.na.GetSolverProperties(routeLayer)
#Set the impedance property to "Meters" to determine the shortest route.
solverProps.impedance = "Meters"
#Resolve the route layer
arcpy.na.Solve(routeLayer)
#Copy the route as a feature class
arcpy.management.CopyFeatures(routesSublayer, shortestRoute)
arcpy.AddMessage("Completed")