摘要
用于访问路径网络分析图层的分析属性。GetSolverProperties 函数用于从路径网络分析图层中获取 RouteSolverProperties 对象。
讨论
RouteSolverProperties 对象提供对路径网络分析图层中所有分析属性的读取和写入权限。该对象可用于修改路径分析图层的分析属性,并且相应的图层可重新求解以确定适合的结果。使用创建路径分析图层地理处理工具可创建新的路径分析图层。通过从新的路径分析图层获取 RouteSolverProperties 对象,可重新对现有图层进行后续分析,而无需每次分析都创建一个新图层,以节省时间。
修改 RouteSolverProperties 对象的属性后,可立即使用其他函数和地理处理工具分析相应图层。无需刷新或更新图层,通过上述对象进行的修改便可生效。
属性
属性 | 说明 | 数据类型 |
accumulators (读写) | 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 (读写) | 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.
| Dictionary |
findBestSequence (读写) | 控制是否重新排序停靠点以查找最优路径。以下是可能值列表:
| String |
impedance (读写) | 用于获取或设置用作阻抗的网络成本属性。当确定最佳路径时,该成本属性最小化。 | String |
orderingType (读写) | 控制当 findBestSequence 属性设置为 FIND_BEST_ORDER 时的停靠点顺序。以下是可能值列表:
| String |
outputPathShape (读写) | 用于获取或设置求解程序输出的路径要素的形状类型。以下是可能值列表:
| String |
restrictions (读写) | 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 (只读) | 返回被用于获取求解程序属性对象的网络分析图层所引用的求解程序的名称。从 RouteSolverProperties 对象访问时,该属性始终返回字符串值 Route Solver。 | String |
timeOfDay (读写) | 用于获取或设置此路径的开始日期和时间。路径开始时间通常用于查找阻抗属性随当日时间变化的路径。例如,开始时间 9 a.m. 可用于查找被认为是高峰时段流量的路径。可以用值 None 指定不应使用任何日期和时间。 可使用以下日期来指定一周中的每一天,而无需使用特定的日期:
例如,要指定路径应该在星期二 5:00 p.m. 开始,则将值指定为 datetime.datetime(1900, 1, 2, 17,0,0)。 timeZoneUsage 参数指定该日期和时间是 UTC 还是首个停靠点所在时区。 | DateTime |
timeZoneUsage (读写) | 指定 timeOfDay 参数的时区。
当求解一个跨多个时区的路径分析并设置起始时间时,orderingType 不可设置为 PRESERVE_NONE。起始位置和时区必须固定。 | String |
uTurns (读写) | 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 |
useHierarchy (读写) | Controls the use of the hierarchy attribute while performing the analysis. The following is a list of possible values:
| String |
useTimeWindows (读写) | 控制是否在停靠点处使用时间窗。以下是可能值列表:
| String |
方法概述
方法 | 说明 |
applyTravelMode (travel_mode) | 根据出行模式对象更新网络分析图层的分析属性。随后可对更新的网络分析图层进行求解以完成分析。 |
方法
applyTravelMode (travel_mode)
参数 | 说明 | 数据类型 |
travel_mode | 该变量引用一个源自网络数据集的出行模式对象。可通过调用 arcpy.na.GetTravelModes 函数获得出行模式对象的列表。 | Object |
创建网络分析图层后,将为其分配所有分析属性的默认值。可使用从网络分析图层获得的求解程序属性对象更新各个分析属性。出行模式存储了一组预定义的分析设置,用于帮助执行特定分析,例如,步行时间出行模式存储了执行基于时间的步行分析所需的分析设置。
使用 applyTravelMode 方法,可一次性应用在一个出行模式中定义的所有分析设置。在分析属性完成更新后,可对网络分析图层进行求解以完成分析。
如果在更新求解程序属性时出错,例如,当提供的出行模式所引用的属性在当前网络数据集中不存在,或不再适用于创建求解程序属性对象的相应网络分析图层所使用的网络数据集时,不会产生任何异常。此方法将成功执行,但当您尝试求解此类网络分析图层时会出现错误。
如果 travel_mode 参数不引用出行模式对象或字符串,则将产生 TypeError 异常。如果 travel_mode 参数引用字符串并且该字符串无法在内部转换成出行模式对象的有效字符串表示,将产生 ValueError 异常。
代码实例
RouteSolverProperties 示例 1(Python 窗口)
此脚本显示如何将阻抗属性更新为“旅行时间”成本属性、指定“分钟”和“米”成本属性作为累积属性以及使用当前时间作为路径的开始时间。它假设已经在新地图文档中根据旧金山地区的教程网络数据集创建名为 Route 的路径网络分析图层。
#Get the route layer object from a layer named "Route" in the table of contents
routeLayer = arcpy.mapping.Layer("Route")
#Get the route solver properties object from the route layer
solverProps = arcpy.na.GetSolverProperties(routeLayer)
#Update the properties for the route layer using the route solver properties object
solverProps.impedance = "TravelTime"
solverProps.accumulators = ["Meters", "Minutes"]
#Only set the time component from the current date time as time of day
solverProps.timeOfDay = datetime.datetime.now().time()
RouteSolverProperties 示例 2(工作流)
此脚本显示如何找出一组停靠点间的最短路径(距离)和最快路径(旅行时间)并在地理数据库中将每个路径另存为要素类。它说明如何只创建一个路径图层实例并使用 RouteSolverProperties 对象将阻抗属性改为所需结果。
import arcpy
#Set up the environment
arcpy.env.overwriteOutput = True
arcpy.CheckOutExtension("network")
#Set up variables
networkDataset = "C:/Data/SanFrancisco.gdb/Transportation/Streets_ND"
stops = "C:/Data/SanFrancisco.gdb/Analysis/Stores"
fastestRoute = "C:/Data/SanFrancisco.gdb/FastestRoute"
shortestRoute = "C:/Data/SanFrancisco.gdb/ShortestRoute"
#Make a new route layer using travel time as impedance to determine fastest route
routeLayer = arcpy.na.MakeRouteLayer(networkDataset, "StoresRoute",
"TravelTime").getOutput(0)
#Get the network analysis class names from the route layer
naClasses = arcpy.na.GetNAClassNames(routeLayer)
#Get the routes sublayer from the route layer
routesSublayer = arcpy.mapping.ListLayers(routeLayer, naClasses["Routes"])[0]
#Load stops
arcpy.na.AddLocations(routeLayer, naClasses["Stops"], stops)
#Solve the route layer
arcpy.na.Solve(routeLayer)
#Copy the route as a feature class
arcpy.management.CopyFeatures(routesSublayer, fastestRoute)
#Get the RouteSolverProperties object from the route layer to modify the
#impedance property of the route layer.
solverProps = arcpy.na.GetSolverProperties(routeLayer)
#Set the impedance property to "Meters" to determine the shortest route.
solverProps.impedance = "Meters"
#Resolve the route layer
arcpy.na.Solve(routeLayer)
#Copy the route as a feature class
arcpy.management.CopyFeatures(routesSublayer, shortestRoute)
arcpy.AddMessage("Completed")
ApplyTravelMode 示例 3(工作流)
此脚本显示基于“货运时间”出行模式查找路径的方法。
#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")
stops = os.path.join(workspace, "TruckStops")
analysis_layer_name = "TruckRoute"
#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.MakeRouteLayer(nds, analysis_layer_name, "TravelTime")
analysis_layer = make_layer_result.getOutput(0)
#Add stops to the analysis layer using default field mappings
sub_layer_names = arcpy.na.GetNAClassNames(analysis_layer)
stops_layer_name = sub_layer_names["Stops"]
arcpy.na.AddLocations(analysis_layer, stops_layer_name, stops, "#", "#")
#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")