Zusammenfassung
Provides access to analysis properties from an origin-destination (OD) cost matrix network analysis layer. The GetSolverProperties function is used to obtain an ODCostMatrixSolverProperties object from an OD cost matrix network analysis layer.
Auswertung
The ODCostMatrixSolverProperties object provides read and write access to all the analysis properties of an OD cost matrix network analysis layer. The object can be used to modify the desired analysis properties of the OD cost matrix layer, and the corresponding layer can be re-solved to determine the appropriate results. A new OD cost matrix layer can be created using the Make OD Cost Matrix Layer geoprocessing tool. Obtaining the ODCostMatrixSolverProperties object from a new OD cost matrix 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 ODCostMatrixSolverProperties 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) | 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 (Lesen und schreiben) | 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 (Lesen und schreiben) | Provides the ability to get or set the default impedance value at which to cut off searching for destinations for a given origin. A value of None is used to specify that no cutoff should be used. | Double |
| defaultTargetDestinationCount (Lesen und schreiben) | Provides the ability to get or set the number of destinations to find for each origin. A value of None is used to specify that all destinations should be found. | 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 routes between origins and destinations. | String |
| outputPathShape (Lesen und schreiben) | Controls whether a straight line is generated between each origin-destination pair in the output OD cost matrix. The following is a list of possible values:
| String |
| restrictions (Lesen und schreiben) | 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 (Nur lesen) | 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 OD Cost Matrix Solver when accessed from a ODCostMatrixSolverProperties object. | String |
| timeOfDay (Lesen und schreiben) | Provides the ability to get or set the departure date and time from the origins. 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 from each origin should start at 8:00 a.m. on Wednesday, specify the value as datetime.datetime(1900, 1, 3, 8,0,0). The timeZoneUsage parameter specifies whether the date and time refer to UTC or the time zone in which the orders are located. | DateTime |
| timeZoneUsage (Lesen und schreiben) | Specifies the time zone of the timeOfDay parameter.
When solving an OD cost matrix analysis that spans across multiple time zones and a start time is set, all origins must be in the same time zone. | String |
| useHierarchy (Lesen und schreiben) | Controls the use of the hierarchy attribute while performing the analysis. The following is a list of possible values:
| String |
| uTurns (Lesen und schreiben) | 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 |
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
ODCostMatrixSolverProperties example 1 (Python window)
The script shows how to update an OD cost matrix network analysis layer to find all destinations within a five-minute cutoff value. It assumes that an OD cost matrix layer called Store Accessibility has been created in a new map document based on the tutorial network dataset for San Francisco region.
#Get the OD cost matrix layer object from a layer named "Store Accessibility" in
#the table of contents
odLayer = arcpy.mapping.Layer("Store Accessibility")
#Get the solver properties object from the OD cost matrix layer
solverProps = arcpy.na.GetSolverProperties(odLayer)
#Update the properties for the OD cost matrix layer using the solver properties
#object
solverProps.defaultCutoff = 5
solverProps.defaultTargetDestinationCount = None
ApplyTravelMode example 2 (workflow)
This script shows how to generate an OD cost matrix 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")
origins = os.path.join(workspace, "Warehouses")
destinations = os.path.join(workspace, "Stores")
analysis_layer_name = "TravelTimeToStores"
#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.MakeODCostMatrixLayer(nds, analysis_layer_name,
"TravelTime")
analysis_layer = make_layer_result.getOutput(0)
#Add origins and destinations to the analysis layer using default field mappings
sub_layer_names = arcpy.na.GetNAClassNames(analysis_layer)
origin_layer_name = sub_layer_names["Origins"]
destination_layer_name = sub_layer_names["Destinations"]
arcpy.na.AddLocations(analysis_layer, origin_layer_name, origins, "#", "#")
arcpy.na.AddLocations(analysis_layer, destination_layer_name, destinations, "#", "#")
#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")