ServiceAreaSolverProperties

Récapitulatif

Provides access to analysis properties from a service area network analysis layer. The GetSolverProperties function is used to obtain a ServiceAreaSolverProperties object from a service area network analysis layer.

Discussion

The ServiceAreaSolverProperties object provides read and write access to all the analysis properties of a service area network analysis layer. The object can be used to modify the desired analysis properties of the service area layer, and the corresponding layer can be re-solved to determine the appropriate results. A new service area layer can be created using the Make Service Area Layer geoprocessing tool. Obtaining the ServiceAreaSolverProperties object from a new service area 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 ServiceAreaSolverProperties 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.

Propriétés

Propriété	Explication	Type de données
accumulators (Lecture/écriture)	Permet d'obtenir ou de définir une liste des attributs de coût du réseau cumulés dans le cadre de l'analyse. Une liste vide, [], indique qu'aucun attribut de coût n'est cumulé.	String
attributeParameters (Lecture/écriture)	Permet d'obtenir ou de définir les attributs paramétrés à utiliser dans l'analyse. La propriété retourne un dictionnaire Python. La clé de dictionnaire est un tuple à deux valeurs comprenant le nom de l'attribut et le nom du paramètre. La valeur de chaque élément du dictionnaire correspond à la valeur du paramètre. Les attributs de réseau paramétrés permettent de modéliser un aspect dynamique de la valeur d'un attribut. Par exemple, un tunnel avec une restriction de hauteur de 12 pieds peut être modélisé à l'aide d'un paramètre. Dans ce cas, la hauteur du véhicule en pieds doit être spécifiée en tant que valeur de paramètre. Si la hauteur du véhicule est supérieure à 12 pieds, cette restriction prend la valeur True, ce qui restreint le passage par le tunnel. De la même façon, un pont peut comporter un paramètre pour spécifier une restriction de poids. Toute tentative de modification de la propriété attributeParameters en place ne permet pas de mettre à jour les valeurs. Vous devez à la place toujours utiliser un nouvel objet dictionnaire pour définir des valeurs pour la propriété. Les deux blocs de code suivants montrent la différence entre ces deux approches. #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 Si la couche d'analyse de réseau ne comporte pas d'attributs paramétrés, cette propriété retourne la valeur Aucun.	Dictionary
defaultBreaks (Lecture/écriture)	Provides the ability to get or set the impedance values, indicating the extent of the service area to be calculated. Multiple polygon breaks can be set to create concentric service areas. For instance, to find 2-, 3-, and 5-minute service areas for the same facility, specify the value as [2, 3, 5].	Double
excludeSources (Lecture/écriture)	Provides the ability to get or set the list of network sources to be excluded when generating the polygons. The geometry of traversed elements from the excluded sources will be omitted from all polygons. An empty list, [], indicates that no network sources are excluded.	String
impedance (Lecture/écriture)	Provides the ability to get or set the network cost attribute used as impedance. This cost attribute is accumulated while determining the service area.	String
includeNetworkSourceFields (Lecture/écriture)	Controls whether additional fields from the underlying source features traversed during the analysis are added to the service area lines. The following is a list of possible values: LINES_SOURCE_FIELDS — Add the SourceID, SourceOID, FromPosition, and ToPosition fields to the service area lines to hold information about the underlying source features traversed during the analysis. This can be useful to join the results of the service area lines to the original source data. A value of True can also be used to specify this option. NO_LINES_SOURCE_FIELDS —Do not add the source fields (SourceID, SourceOID, FromPosition, and ToPosition) to the service area lines. A value of False can also be used to specify this option.	String
lineOverlap (Lecture/écriture)	Controls whether overlapping lines are generated when the service area lines are computed. The following is a list of possible values: OVERLAP — Include a separate line feature for each facility when the facilities have service area lines that are coincident. A value of True can also be used to specify this option. NON_OVERLAP — Include each service area line once and associate it with its closest (least impedance) facility. A value of False can also be used to specify this option.	String
lineType (Lecture/écriture)	Provides the ability to get or set the type of service area lines to be generated from the analysis. The following is a list of possible values: NO_LINES —Do not generate lines. TRUE_LINES —Lines are generated without measures. TRUE_LINES_WITH_MEASURES —Lines are generated with measures. The measure values are generated based on the impedance value on each end of the edge with the intermediate vertices interpolated. Do not use this option if faster performance is desired.	String
polygonMerge (Lecture/écriture)	Controls whether polygons that share similar break values are merged. This option is applicable only when generating polygons for multiple facilities. The following is a list of possible values: NO_MERGE —Create individual polygons for each facility. The polygons can overlap each other. NO_OVERLAP —Create individual polygons that are closest for each facility. The polygons do not overlap each other. MERGE — Join the polygons of multiple facilities that have the same break value.	String
polygonNesting (Lecture/écriture)	Controls whether concentric service area polygons are created as disks or rings. This option is applicable only when multiple break values are specified for the facilities. The following is a list of possible values: RINGS —Do not include the area of the smaller breaks. This creates polygons going between consecutive breaks. Use this option if you want to find the area from one break to another. A value of True can also be used to specify this option. DISKS — Create the polygons going from the facility to the break. For instance, If you create 5- and 10-minute service areas, then the 10-minute service area polygon will include the area under the 5-minute service area polygon. Use this option if you want to find the entire area from the facility to the break for each break. A value of False can also be used to specify this option.	String
polygonType (Lecture/écriture)	Provides the ability to get or set the type of polygons to be generated. The following is a list of possible values: SIMPLE_POLYS —Create generalized polygons that are generated quickly and are fairly accurate, except on the fringes. DETAILED_POLYS —Create detailed polygons that accurately model the service area lines and may contain islands of unreached areas. This option is a lot slower than generating generalized polygons. NO_POLYS —Turns off polygon generation for the case in which only service area lines are desired.	String
restrictions (Lecture/écriture)	Permet d'obtenir ou de définir une liste des attributs de restriction appliqués pour l'analyse. Une liste vide, [], indique qu'aucun attribut de restriction n'est utilisé pour l'analyse.	String
solverName (Lecture seule)	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 Service Area Solver when accessed from a ServiceAreaSolverProperties object.	String
splitLinesAtBreaks (Lecture/écriture)	Controls whether service area lines are split when they cross a break value. The following is a list of possible values: SPLIT —Split every line between two breaks into two lines, each lying within its break. This is useful if you want to symbolize the service area lines by break; otherwise, use the NO_SPLIT option for optimal performance. NO_SPLIT —The lines are not split at the boundaries of the breaks.	String
timeOfDay (Lecture/écriture)	Provides the ability to get or set the time to depart from or arrive at the facilities. The interpretation of this value depends on whether travel is toward or away from the facilities. It represents the departure time if the travelDirection property is set to TRAVEL_FROM and represents the arrival time if the travelDirection property is set to TRAVEL_TO. 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: Aujourd'hui - 12/30/1899 Dimanche - 12/31/1899 Lundi - 1/1/1900 Mardi - 1/2/1900 Mercredi - 1/3/1900 Jeudi - 1/4/1900 Vendredi - 1/5/1900 Samedi - 1/6/1900 For example, to specify that the departure from facilities should occur at 8:00 a.m. on Friday, specify the value as datetime.datetime(1900, 1, 5, 8,0,0). The timeZoneUsage parameter specifies whether the date and time refer to UTC or the time zone in which the facilities are located.	DateTime
timeZoneUsage (Lecture/écriture)	Specifies the time zone or zones of the timeOfDay parameter. GEO_LOCAL —The timeOfDay parameter refers to the time zone or zones in which the facilities are located. Therefore, the start or end times of the service areas are staggered by time zone.Setting timeOfDay to 9:00 a.m., choosing GEO_LOCAL, then solving causes service areas to be generated for 9:00 a.m. Eastern Time for any facilities in the Eastern Time Zone, 9:00 a.m. Central Time for facilities in the Central Time Zone, 9:00 a.m. Mountain Time for facilities in the Mountain Time Zone, and so on, for facilities in different time zones. The time is always 9:00 a.m. local time, but staggered in real time.If stores in a chain that span the U.S. open at 9:00 a.m. local time, this parameter value could be chosen to find market territories at opening time for all stores in one solve. First, the stores in the Eastern Time Zone open and a polygon is generated, stores open an hour later in Central Time, and so on. UTC —The timeOfDay parameter refers to Coordinated Universal Time (UTC). Therefore, all facilities are reached or departed from simultaneously, regardless of the time zone or zones they are in.Setting timeOfDay to 2:00 p.m., choosing UTC, then solving causes service areas to be generated for 9:00 a.m. Eastern Standard Time for any facilities in the Eastern Time Zone, 8:00 a.m. Central Standard Time for facilities in the Central Time Zone, 7:00 a.m. Mountain Standard Time for facilities in the Mountain Time Zone, and so on, for facilities in different time zones. Remarque : The scenario above assumes standard time. During daylight saving time, the Eastern, Central, and Mountain times would each be one hour ahead (that is, 10:00, 9:00, and 8:00 a.m., respectively). One of the cases in which the UTC option is useful is to visualize emergency-response coverage for a jurisdiction that is split into two time zones. The emergency vehicles are loaded as facilities. timeOfDay is set to now in UTC. (You need to determine the current time and date in UTC to correctly use this option.) Other properties are set, and the analysis is solved. Even though a time-zone boundary divides the vehicles, the results show areas that can be reached given current traffic conditions. This same process can be used for other times as well, not just for now. Irrespective of the timeZoneUsage setting, all facilities must be in the same time zone when timeOfDay has a nonnull value and polygonMerge is set to create merged or nonoverlapping polygons.	String
travelDirection (Lecture/écriture)	Controls the direction in which the impedance is accumulated during service area analysis. The following is a list of possible values: TRAVEL_FROM —The service area is created in the direction away from the facilities. TRAVEL_TO —The service area is created in the direction toward the facilities.	String
trimDistance (Lecture/écriture)	Provides the ability to get or set the distance within which the service area polygons are trimmed. The property value includes a numeric value and a unit for the distance separated by a space; for example, to specify a trim distance of 100 Meters, use "100 Meters".	String
trimPolygons (Lecture/écriture)	Controls whether the service area polygons are trimmed. The following is a list of possible values: TRIM_POLYS —Trim the polygons containing the edges at the periphery of the service area to be within the specified distance of these outer edges. This is useful if the network is very sparse and you don't want the service area to cover large areas where there are no features. A value of True can also be used to specify this option. NO_TRIM_POLYS —Do not trim polygons. A value of False can also be used to specify this option.	String
useHierarchy (Lecture/écriture)	Contrôle l'utilisation de l'attribut de hiérarchie lors de l'analyse. Voici une liste des valeurs possibles : USE_HIERARCHY — Utilise l'attribut de hiérarchie pour l'analyse. L'utilisation d'une hiérarchie implique une préférence du solveur pour les tronçons d'ordre supérieur par rapport aux tronçons d'ordre inférieur. Les recherches hiérarchiques sont plus rapides et permettent de simuler la préférence d'un chauffeur de circuler sur des autoroutes au lieu de routes locales si possible, même si cela implique un trajet plus long. Cette option s'applique uniquement si le jeu de données réseau référencé par la couche ArcGIS Network Analyst dispose d'un attribut de hiérarchie. Une valeur True peut également être utilisée pour spécifier cette option. NO_HIERARCHY —N'utilise pas l'attribut de hiérarchie pour l'analyse. Un itinéraire exact est alors obtenu pour le jeu de données réseau. Une valeur False peut également être utilisée pour spécifier cette option.	String
uTurns (Lecture/écriture)	Permet d'obtenir ou de définir la stratégie qui indique comment les demi-tours aux jonctions qui pourraient survenir pendant la traversée du réseau entre différents arrêts sont gérés par le solveur. Voici une liste des valeurs possibles : ALLOW_UTURNS —Les demi-tours sont autorisés aux jonctions comportant un nombre quelconque de tronçons connectés. NO_UTURNS —Les demi-tours sont interdits à toutes les jonctions, indépendamment de la valence de jonction. Notez toutefois que les demi-tours restent autorisés aux emplacements réseau même lorsque ce paramètre est sélectionné ; en revanche, vous pouvez configurer la propriété CurbApproach des emplacements réseau individuels pour y interdire les demi-tours également. ALLOW_DEAD_ENDS_ONLY —Les demi-tours sont interdits au niveau de toutes les jonctions, sauf celles ayant un seul tronçon adjacent (voie sans issue). ALLOW_DEAD_ENDS_AND_INTERSECTIONS_ONLY —Les demi-tours sont interdits aux jonctions où deux tronçons adjacents se rencontrent, mais sont autorisés aux intersections (jonctions avec au moins trois tronçons adjacents) et aux voies sans issue (jonctions avec exactement un tronçon adjacent). Souvent, les réseaux comportent des jonctions superflues au milieu de segments de route. Cette option empêche des véhicules de faire des demi-tours à ces emplacements.	String

Vue d'ensemble des méthodes

Méthode	Explication
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.

Méthodes

applyTravelMode (travel_mode)

Paramètre	Explication	Type de données
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.	String

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.

Remarque :

When you apply a travel mode whose useHierarchy property is set to True, and the service area network analyst layer references a network dataset that includes a service area index optimization, the hierarchy isn't used; the service-area index is used instead.

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.

Exemple de code

ServiceAreaSolverProperties example 1 (Python window)

The script shows how to update a service area network analysis layer to use hierarchy and set 5, 10, and 15 minutes as the break values. It assumes that a service area layer called Store Trade Areas has been created in a new map document based on the tutorial network dataset for San Francisco region.

#Get the service area layer object from a layer named "Store Trade Areas" in
#the table of contents
saLayer = arcpy.mapping.Layer("Store Trade Areas")

#Get the solver properties object from the service area layer
solverProps = arcpy.na.GetSolverProperties(saLayer)

#Update the properties for the service area layer using the solver properties
#object
solverProps.defaultBreaks = [5, 10, 15]
solverProps.useHierarchy = "USE_HIERARCHY"

ApplyTravelMode example 2 (workflow)

This script shows how to generate a service area 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, "Warehouses")
analysis_layer_name = "ServiceAreas"

#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.MakeServiceAreaLayer(nds, analysis_layer_name,
                                                  "TravelTime")
analysis_layer = make_layer_result.getOutput(0)

#Add facilities to the analysis layer using default field mappings         
sub_layer_names = arcpy.na.GetNAClassNames(analysis_layer)
facilities_layer_name = sub_layer_names["Facilities"]
arcpy.na.AddLocations(analysis_layer, facilities_layer_name, facilities, "#", "#")

#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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