描述
根据指定为参数的网络分析图层类型返回 Network Analyst 求解程序属性对象。求解程序属性对象被用于更新图层的分析属性。
讨论
当修改网络分析图层的分析属性时，GetSolverProperties 用作主入口点。它根据网络分析图层返回单独的求解程序属性对象。系统提供以下六种类型的求解程序属性对象：RouteSolverProperties、ClosestFacilitySolverProperties、ServiceAreaSolverProperties、ODCostMatrixSolverProperties、VehicleRoutingProblemSolverProperties 和 LocationAllocationSolverProperties。每个求解程序属性对象都提供了对特定于某个网络分析图层的分析属性的读写访问权限。
语法
GetSolverProperties (network_analyst_layer)
| 参数 | 说明 | 数据类型 |
network_analyst_layer | 该变量引用一个从网络分析图层获取的 Layer 对象。该对象可以源自地图文档中的现有图层或向网络分析图层文件指定目录路径作为 Layer 类的参数。可以使用 Layer 对象上的 isNetworkAnalystLayer 属性来确认某个给定的 Layer 对象是否为网络分析图层。 | Layer |
| 数据类型 | 说明 |
| Object | 与网络分析图层类型对应的求解程序属性对象。 |
代码示例
此示例显示了如何使用 GetSolverProperties 访问网络分析图层的求解程序属性对象以及如何使用该求解程序属性对象更新分析设置。
# Name: GetSolverProperties_01.py
# Description: Generate 3-minute service areas around fire stations at several
# times of day to compare coverage differences due to varying
# traffic conditions. Use GetSolverProperties to access the
# Service Area layer's solver properties object, and update the
# time of day property prior to each solve.
# Requirements: Network Analyst Extension
#Import system modules
import arcpy
from arcpy import env
import os, datetime
try:
#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/SanFrancisco.gdb"
network = os.path.join(input_gdb, "Transportation", "Streets_ND")
layer_name = "FireStationCoverage"
out_featureclass = os.path.join(output_dir, "Output.gdb",
"FireStationCoverage")
travel_mode = "Driving Time"
facilities = os.path.join(input_gdb, "Analysis", "FireStations")
times_of_day = [datetime.datetime(2014, 9, 25, 7, 0, 0),
datetime.datetime(2014, 9, 25, 12, 30, 0),
datetime.datetime(2014, 9, 25, 17, 30, 0),
datetime.datetime(2014, 9, 25, 21, 0, 0)]
#Create a new service area layer.
result_object = arcpy.na.MakeServiceAreaAnalysisLayer(network, layer_name,
travel_mode, "FROM_FACILITIES",
[3], polygon_detail="HIGH",
geometry_at_overlaps="OVERLAP")
#Get the layer object from the result object. The service area layer can
#now be referenced using the layer object.
layer_object = result_object.getOutput(0)
#Get the names of all the sublayers within the service area layer.
sublayer_names = arcpy.na.GetNAClassNames(layer_object)
#Stores the layer names that we will use later
facilities_layer_name = sublayer_names["Facilities"]
polygons_layer_name = sublayer_names["SAPolygons"]
#The input data has a field for FireStationID that we want to transfer to
#our analysis layer. Add the field, and then use field mapping to transfer
#the values.
arcpy.na.AddFieldToAnalysisLayer(layer_object, facilities_layer_name,
"FireStationID", "TEXT")
field_mappings = arcpy.na.NAClassFieldMappings(layer_object,
facilities_layer_name)
field_mappings["FireStationID"].mappedFieldName = "FireStationID"
#Load the fire stations as facilities.
arcpy.na.AddLocations(layer_object, facilities_layer_name, facilities,
field_mappings, "")
# Add fields to the output Polygons sublayer for later use.
arcpy.na.AddFieldToAnalysisLayer(layer_object, polygons_layer_name,
"FireStationID", "TEXT")
arcpy.na.AddFieldToAnalysisLayer(layer_object, polygons_layer_name,
"TimeOfDay", "TEXT")
#Get sublayers to work with later
facilities_sublayer = layer_object.listLayers(facilities_layer_name)[0]
polygons_sublayer = layer_object.listLayers(polygons_layer_name)[0]
#Get the Service Area Layer's solver properties. This can be used to
#set individual properties later without re-creating the layer.
solver_properties = arcpy.na.GetSolverProperties(layer_object)
#Solve the Service Area for each time of day in the time list
for t in times_of_day:
print("Calculating service area for time of day: ", t)
#Use the solver properties to set the time of day for the solve
solver_properties.timeOfDay = t
#Solve the service area layer
arcpy.na.Solve(layer_object)
#Transfer the FireStationID field from the input Facilities to the
#output Polygons
arcpy.management.AddJoin(polygons_sublayer, "FacilityID",
facilities_sublayer, "ObjectID")
#The joined fields are qualified by the feature class name of the joined
#table, so determine the feature class names
field_qualifier_pol = os.path.basename(polygons_sublayer.dataSource)
target_field_name = "%s.FireStationID" % field_qualifier_pol
field_qualifier_fac = os.path.basename(facilities_sublayer.dataSource)
expression = "!%s.FireStationID!" % field_qualifier_fac
arcpy.management.CalculateField(polygons_sublayer, target_field_name,
expression, "PYTHON")
arcpy.management.RemoveJoin(polygons_sublayer)
#Populate the TimeOfDay field in the output feature class
expression = '"' + str(t) + '"'
arcpy.management.CalculateField(polygons_sublayer, "TimeOfDay",
expression, "PYTHON")
#Append the polygons to the output feature class. If this was the first
#solve, create the feature class.
if not arcpy.Exists(out_featureclass):
arcpy.management.CopyFeatures(polygons_sublayer, out_featureclass)
else:
arcpy.management.Append(polygons_sublayer, out_featureclass)
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))