GetSolverProperties

摘要

根据指定为参数的网络分析图层类型返回网络分析求解程序属性对象。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。求解程序属性对象有以下六种类型：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图层对象。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。可以使用图层对象上的 isNetworkAnalystLayer 属性来确认某个给定的对象图层是否为网络分析图层。	Layer

返回值

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

GetSolverProperties 示例

该示例显示如何使用 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 datetime
import arcpy
from arcpy import env

try:
    #Check out the Network Analyst extension license
    arcpy.CheckOutExtension("Network")

    #Set environment settings
    env.workspace = "C:/Data/SanFrancisco.gdb"
    env.overwriteOutput = True

    #Set local variables
    inNetworkDataset = "Transportation/Streets_ND"
    outNALayerName = "FireStationCoverage"
    outSAFC = "Analysis/outSAPolys"
    impedanceAttribute = "TravelTime"
    inFacilities = "Analysis/FireStations"
    timelist = [datetime.datetime(2013, 8, 23, 7, 0, 0),
                datetime.datetime(2013, 8, 23, 12, 30, 0),
                datetime.datetime(2013, 8, 23, 17, 30, 0),
                datetime.datetime(2013, 8, 23, 21, 0, 0)]

    #Create a new service area layer.
    outSAResultObject = arcpy.na.MakeServiceAreaLayer(inNetworkDataset, outNALayerName,
                                  impedanceAttribute, "TRAVEL_FROM", "3",
                                  "DETAILED_POLYS", "NO_MERGE",
                                  hierarchy = "NO_HIERARCHY")

    #Get the layer object from the result object. The service area layer can
    #now be referenced using the layer object.
    outNALayer = outSAResultObject.getOutput(0)

    #Get the names of all the sublayers within the service area layer.
    subLayerNames = arcpy.na.GetNAClassNames(outNALayer)
    #Store the layer names that we will use later
    facilitiesLayerName = subLayerNames["Facilities"]
    polygonsLayerName = subLayerNames["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(outNALayer, facilitiesLayerName,
                                                    "FireStationID", "TEXT")
    fieldMappings = arcpy.na.NAClassFieldMappings(outNALayer,
                                                    facilitiesLayerName)
    fieldMappings["FireStationID"].mappedFieldName = "FireStationID"

    #Load the fire stations as facilities.
    arcpy.na.AddLocations(outNALayer, facilitiesLayerName, inFacilities,
                            fieldMappings, "",
                            exclude_restricted_elements = "EXCLUDE")

    #Get sublayers we will want to work with later
    FacilitiesSubLayer = arcpy.mapping.ListLayers(outNALayer,
                                                    facilitiesLayerName)[0]
    PolygonsSubLayer = arcpy.mapping.ListLayers(outNALayer,
                                                    polygonsLayerName)[0]

    # Add fields to the output Polygons sublayer. We will fill the values later.
    arcpy.na.AddFieldToAnalysisLayer(outNALayer, polygonsLayerName,
                                        "FireStationID", "TEXT")
    arcpy.na.AddFieldToAnalysisLayer(outNALayer, polygonsLayerName,
                                        "TimeOfDay", "TEXT")

    #Get the Service Area Layer's solver properties. This will allow us to
    #set individual properties later without re-creating the layer.
    SA_SolverProperties = arcpy.na.GetSolverProperties(outNALayer)

    #Solve the Service Area for each time of day in our time list
    for t in timelist:

        print "Now solving for time of day: " + t

        #Use the solver properties to set the time of day for the solve
        SA_SolverProperties.timeOfDay = t

        #Solve the service area layer
        arcpy.na.Solve(outNALayer)

        #Transfer the FireStationID field from the input Facilities to the
        #output Polygons
        arcpy.management.AddJoin(PolygonsSubLayer, "FacilityID",
                                        FacilitiesSubLayer, "ObjectID")
        arcpy.management.CalculateField(PolygonsSubLayer, "FireStationID",
                                        "!Facilities.FireStationID!", "PYTHON")
        arcpy.management.RemoveJoin(PolygonsSubLayer)

        #Populate the TimeOfDay field
        expression = '"' + t + '"'
        arcpy.management.CalculateField(PolygonsSubLayer, "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(outSAFC):
            arcpy.management.CopyFeatures(PolygonsSubLayer, outSAFC)
        else:
            arcpy.management.Append(PolygonsSubLayer, outSAFC)

    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)