ClosestFacilitySolverProperties

Zusammenfassung

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.

Diskussion

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 re-solved to determine the appropriate results. A new closest facility layer can be created using the Make Closest Facility 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 new 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.

Eigenschaften

Eigenschaft	Erläuterung	Datentyp
accumulators (Lesen und schreiben)	Ermöglicht das Abrufen oder Festlegen einer Liste der Netzwerk-Kostenattribute, die als Teil der Analyse akkumuliert werden. Eine leere Liste, [], weist darauf hin, dass keine Kostenattribute akkumuliert werden.	String
attributeParameters (Lesen und schreiben)	Ermöglicht das Abrufen oder Festlegen der parametrierten Attribute, die für die Analyse verwendet werden sollen. Die Eigenschaft gibt ein Python-Wörterbuch zurück. Der Wörterbuchschlüssel ist ein Tupel mit zwei Werten, der aus dem Attributnamen und dem Parameternamen besteht. Der Wert der einzelnen Elemente im Wörterbuch ist der Parameterwert. Mithilfe der parametrierten Netzwerkattribute können dynamische Aspekte eines Attributwertes modelliert werden. So kann beispielsweise ein Tunnel mit einer Höhenbeschränkung von 12 Fuß mit einem Parameter modelliert werden. In diesem Fall sollte die Höhe des Fahrzeugs (in Fuß) als angegebener Parameterwert verwendet werden. Wenn das Fahrzeug höher als 12 Fuß ist, wird diese Einschränkung als "Wahr" bewertet und das Passieren des Tunnels somit untersagt. Entsprechend kann eine Brücke einen Parameter zur Angabe einer Gewichtsbeschränkung aufweisen. Das Ändern der festgelegten Eigenschaft " attributeParameters" würde keine aktualisierten Werte zurückgeben. Sie sollten daher immer ein neues Wörterbuchobjekt verwenden, um die Werte für die Eigenschaft festzulegen. Die zwei folgenden Codeblöcke veranschaulichen den Unterschied zwischen diesen beiden Ansätzen: #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 Wenn der Netzwerkanalyse-Layer keine parametrierten Attribute aufweist, gibt diese Eigenschaft None zurück.	Dictionary
defaultCutoff (Lesen und schreiben)	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 (Lesen und schreiben)	Provides the ability to get or set the number of closest facilities to find per incident.	Integer
impedance (Lesen und schreiben)	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 (Lesen und schreiben)	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: TRUE_LINES_WITH_MEASURES —The output routes will have the exact shape of the underlying network sources. Furthermore, the output includes route measurements for linear referencing. The measurements increase from the first stop and record the cumulative impedance to reach a given position. TRUE_LINES_WITHOUT_MEASURES —The output routes will have the exact shape of the underlying network sources. STRAIGHT_LINES —The output route shape will be a single straight line between each of the incident-facility pair. NO_LINES —No shape will be generated for the output routes.	String
restrictions (Lesen und schreiben)	Ermöglicht das Abrufen oder Festlegen einer Liste der Restriktionsattribute, die für die Analyse angewendet werden. Eine leere Liste, [], weist darauf hin, dass keine Restriktionsattribute für die Analyse verwendet werden.	String
solverName (Schreibgeschützt)	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
timeOfDay (Lesen und schreiben)	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. Heute – 30.12.1899 Sonntag – 31.12.1899 Montag – 1.1.1900 Dienstag – 2.1.1900 Mittwoch – 3.1.1900 Donnerstag – 4.1.1900 Freitag – 5.1.1900 Samstag – 06.01.1900 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 (Lesen und schreiben)	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: END_TIME —The routes arrive at the facilities or incidents at the time you set in the timeOfDay property. This choice is useful if arrival time is more important; that is, you want to know what time you need to leave in order to arrive at your destination at a given time. START_TIME —The routes depart from the facilities or incidents at the time you set in the timeOfDay property. This choice is useful to find the best routes given a departure time. NOT_USED —The routes do not use a start or end time and date. This choice should be used if the timeOfDay property has a value of None.	String
timeZoneUsage (Lesen und schreiben)	Specifies the time zone of the timeOfDay parameter. GEO_LOCAL —The timeOfDay parameter refers to the time zone in which the facilities or incidents are located. If timeOfDayUsage is set to Start_Time and travelDirection is TRAVEL_FROM, this is the time zone of the facilities. If timeOfDayUsage is set to Start_Time and travelDirection is TRAVEL_TO, this is the time zone of the incidents. If timeOfDayUsage is set to End_Time and travelDirection is TRAVEL_FROM, this is the time zone of the incidents. If timeOfDayUsage is set to End_Time and travelDirection is TRAVEL_TO, this is the time zone of the facilities. UTC —The timeOfDay parameter refers to Coordinated Universal Time (UTC). Choose this option if you want to find what's nearest for a specific time, such as now, but aren't certain in which time zone the facilities or incidents will be located. Irrespective of the timeZoneUsage setting, if your facilities and incidents are in multiple time zones, the following rules are enforced by the tool: All incidents must be in the same time zone when Specifying a start time and traveling from incident to facility Specifying an end time and traveling from facility to incident All facilities must be in the same time zone when Specifying a start time and traveling from facility to incident Specifying an end time and traveling from incident to facility	String
travelDirection (Lesen und schreiben)	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: TRAVEL_FROM —Direction of travel is from facilities to incidents. TRAVEL_TO —Direction of travel is from incidents to facilities.	String
useHierarchy (Lesen und schreiben)	Steuert die Verwendung des Hierarchieattributs während der Durchführung der Analyse. Nachfolgend finden Sie eine Liste der möglichen Werte: USE_HIERARCHY — Verwenden Sie das Hierarchieattribut für die Analyse. Wenn eine Hierarchie verwendet wird, werden vom Solver Kanten einer höheren Rangstufe gegenüber Kanten niedrigerer Rangstufen bevorzugt. Hierarchische Berechnungen sind schneller und können verwendet werden, um die Präferenzen eines Fahrers auf der Straße zu simulieren, der – wenn möglich – lieber auf Autobahnen statt auf Landstraßen fährt, selbst wenn die Fahrstrecke dann länger ist. Diese Option ist nur verfügbar, wenn das Netzwerk-Dataset, auf das vom ArcGIS Network Analyst-Layer verwiesen wird, über ein Hierarchieattribut verfügt. Diese Option kann auch über den Wert True festgelegt werden. NO_HIERARCHY —Verwenden Sie das Hierarchieattribut nicht für die Analyse. Wird keine Hierarchie verwendet, dann wird eine genaue Route für das Netzwerk-Dataset berechnet. Diese Option kann auch über den Wert False festgelegt werden.	String
uTurns (Lesen und schreiben)	Ermöglicht das Abrufen oder Festlegen der Richtlinie, die angibt, wie der Solver Wenden an Knoten, die beim Durchlaufen des Netzwerks zwischen Stopps auftreten können, verarbeitet. Nachfolgend finden Sie eine Liste der möglichen Werte: ALLOW_UTURNS —Wenden sind an Knoten mit einer beliebigen Anzahl verbundener Kanten erlaubt. NO_UTURNS —Wenden sind an allen Knoten verboten, unabhängig von der Valenz der Knoten. Beachten Sie, dass Wenden an Netzwerkstandorten auch dann erlaubt sind, wenn diese Einstellung ausgewählt wurde. Sie können jedoch die Eigenschaft "CurbApproach" der einzelnen Netzwerkstandorte festlegen, um auch hier Wenden zu verbieten. ALLOW_DEAD_ENDS_ONLY —Wenden sind an allen Knoten verboten, außer es ist nur eine angrenzende Kante vorhanden (Sackgasse). ALLOW_DEAD_ENDS_AND_INTERSECTIONS_ONLY —Wenden sind an Knoten verboten, an denen genau zwei angrenzende Kanten aufeinander treffen, jedoch an Kreuzungen (Knoten mit drei oder mehr angrenzenden Kanten) und in Sackgassen (Knoten mit genau einer angrenzenden Kante) erlaubt. Oftmals verfügen Netzwerke über unwesentliche Knoten in der Mitte von Straßensegmenten. Durch diese Option wird verhindert, dass Fahrzeuge an diesen Punkten wenden.	String

Methodenübersicht

Methode	Erläuterung
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.

Methoden

applyTravelMode (travel_mode)

Parameter	Erläuterung	Datentyp
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.

Codebeispiel

ClosestFacilitySolverProperties example 1 (Python window)

The script shows how to update a closest facility network analysis layer to find three facilities without using a cutoff value. It assumes that a closest facility layer called Closest Hospitals has been created in a new map document based on the tutorial network dataset for San Francisco region.

#Get the closest facility layer object from a layer named "Closest Hospitals" in
#the table of contents
cfLayer = arcpy.mapping.Layer("Closest Hospitals")

#Get the closest facility solver properties object from the closest facility layer
solverProps = arcpy.na.GetSolverProperties(cfLayer)

#Update the properties for the closest facility layer using the closest facility
#solver properties object
solverProps.defaultCutoff = None
solverProps.defaultTargetFacilityCount = 3

ApplyTravelMode example 2 (workflow)

This script shows how to find closest facilities based on a Trucking Time travel mode.

#Import modules
import os
import arcpy

#Define variables
workspace = "C:/data/SanDiego.gdb"
output_folder = "C:/data/output"
nds = os.path.join(workspace, "Transportation", "Streets_ND")
facilities = os.path.join(workspace, "WeightStations")
incidents = os.path.join(workspace, "RestAreaLocations")
analysis_layer_name = "ClosestFacility"

#Set environment variables
arcpy.env.overwriteOutput = True

#Check out the network analyst extension
arcpy.CheckOutExtension("network")

#Create a new closest facility analysis layer
make_layer_result = arcpy.na.MakeClosestFacilityLayer(nds, analysis_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(nds)
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 = os.path.join(output_folder, analysis_layer_name + ".lyr")
arcpy.management.SaveToLayerFile(analysis_layer, output_layer, "RELATIVE")

arcpy.AddMessage("Completed")

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