RouteSolverProperties (arcpy.na)

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 对象用于读取路径网络分析图层的所有分析属性。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，可重用现有图层进行后续分析，而无需每次分析都创建一个新的图层，以节省时间。

修改 RouteSolverProperties 对象的属性后，相应的图层可立即与其他函数和地理处理工具配合使用。无需刷新或更新图层，通过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.

#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
If the network analysis layer does not have parameterized attributes, this property returns None.

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：

  • FIND_BEST_ORDER —将重新排序停靠点以查找最佳路径。此选项将路径分析由最短路径问题变为流动推销员问题 (TSP)。值 True 也可用于指定此选项。
  • USE_INPUT_ORDER —将按照输入顺序访问停靠点。值 False 也可用于指定此选项。
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：

  • PRESERVE_BOTH —按输入顺序保留第一个和最后一个停靠点作为路径中相应的第一个和最后一个停靠点。
  • PRESERVE_FIRST —按输入顺序保留第一个停靠点作为路径中相应的第一个停靠点，而最后一个停靠点可以被重新排序。
  • PRESERVE_LAST —按输入顺序保留最后一个停靠点作为路径中相应的最后一个停靠点，而第一个停靠点可以被重新排序。
  • PRESERVE_NONE —第一个和最后一个停靠点都可以被重新排序。
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：

  • TRUE_LINES_WITH_MEASURES —输出路径将具有基础网络源的精确形状。而且，输出还包括线性参考的路径测量值。测量值从第一个停靠点增加并将记录到达指定位置的累积阻抗。
  • TRUE_LINES_WITHOUT_MEASURES —输出路径将具有基础网络源的精确形状。
  • STRAIGHT_LINES —输出路径形状为两个停靠点之间的一条直线。
  • NO_LINES —将不会为输出路径生成任何形状。
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：

  • 今天 - 12/30/1899
  • 星期日 - 12/31/1899
  • 星期一 - 1/1/1900
  • 星期二 - 1/2/1900
  • 星期三 - 1/3/1900
  • 星期四 - 1/4/1900
  • 星期五 - 1/5/1900
  • 星期六 - 1/6/1900

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。

  • GEO_LOCAL —timeOfDay 参数是指首个停靠点所在的时区。
  • UTC —timeOfDay 参数是指协调世界时间 (UTC)。如果您想要在指定时间内（如现在）求解分析问题，但不确定设施点或请求点所在的时区，请选择此选项。

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:

  • ALLOW_UTURNS —U-turns are permitted at junctions with any number of connected edges.
  • NO_UTURNS —U-turns are prohibited at all junctions, regardless of junction valency. Note, however, that U-turns are still permitted at network locations even when this setting is chosen; however, you can set the individual network locations' CurbApproach property to prohibit U-turns there as well.
  • ALLOW_DEAD_ENDS_ONLY —U-turns are prohibited at all junctions, except those that have only one adjacent edge (a dead end).
  • ALLOW_DEAD_ENDS_AND_INTERSECTIONS_ONLY —U-turns are prohibited at junctions where exactly two adjacent edges meet but are permitted at intersections (junctions with three or more adjacent edges) and dead ends (junctions with exactly one adjacent edge). Oftentimes, networks have extraneous junctions in the middle of road segments. This option prevents vehicles from making U-turns at these locations.
String
useHierarchy
(读写)

Controls the use of the hierarchy attribute while performing the analysis. The following is a list of possible values:

  • USE_HIERARCHY — Use the hierarchy attribute for the analysis. Using a hierarchy results in the solver preferring higher-order edges to lower-order edges. Hierarchical solves are faster, and they can be used to simulate the preference of a driver who chooses to travel on freeways over local roads when possible—even if that means a longer trip. This option is applicable only if the network dataset referenced by the Network Analyst layer has a hierarchy attribute. A value of True can also be used to specify this option.
  • NO_HIERARCHY —Do not use the hierarchy attribute for the analysis. Not using a hierarchy yields an exact route for the network dataset. A value of False can also be used to specify this option.
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：

  • USE_TIMEWINDOWS —路径将在停靠点处使用时间窗。如果在时间窗之前到达停靠点，则在时间窗打开前将会有一段等待时间。如果在时间窗之后到达停靠点，将会出现时间窗冲突。当计算路径时，最小阻抗抵消了总的时间窗冲突。仅当指定为阻抗属性的网络成本属性使用时间单位时，此选项才适用。值 True 也可用于指定此选项。
  • NO_TIMEWINDOWS —路径将在停靠点处忽略时间窗。值 False 也可用于指定此选项。
String

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")

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路径分析
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5/10/2014