Location-Allocation

Instructions for use

Location-Allocation, which selects the best location from multiple candidate locations according to the specified parameters. Location-Allocation analysis provides a reference for the location of service facilities. For more information about Location-Allocation, see the Location-Allocation Overview page.

Operation steps

  1. Open the Network Dataset you want to analyze.
  2. On the Traffic Analysis tab, in the Road Network Analysis group, select the Environment Settings check box to bring up the Environment Settings window. In this window, you can set the Basic Parameters of Network Analysis (such as Weight Field, Node/Edge ID Field, etc.), Analyst Result parameters, and parameters for tracking analysis (only required for tracking analysis). For an introduction to the Environment Settings window, see Network AnalysisEn vironment Settings window .
  3. Create a new instance of the Location-Allocation analysis. On the Traffic Analysis tab, in the Road Network Analysis group, click the gallery Drop-down Button and select the Location-Allocation item from the drop-down box. Upon successful creation, the Instance Management window automatically pops up. And the mouse state in the Map changes to the drawing state to add a center point.
  4. Adds a center point to the current network layer. The central point, also known as the resource center supply point, is the facility point that provides resources and services. There are two ways to add a center point. One way is to add a center point in the network layer through Draw. The other way is to import a Point Dataset as a center point in the Manage Center Stop window.
    • Add by Mouse Center Point

      In the toolbar of Instance Management window, click the Add by Mouse "button. At this time, the mouse in the Map turns to the drawing status. You can click the Add by Mouse site in the appropriate position in the Map. Each time a center point is added, it is automatically added to the center point information in the Instance Management window. When you are done, right-click to end the operation. Note: The appropriate Node Tolerance needs to be set. If the mouse click position exceeds the Node Tolerance, the site addition may fail.

    • Import Center Point Import the Point Dataset in the

      Current Works pace as the center point. Select the Center Point node from the directory tree in the Instance Management "window, and select the Manage Center Stop" item from the Context Menu to open the Manage Center Stop "window. In the dialog box, import the center point through the import command, and perform Parameter Settings. For an introduction to the Manage Center Stop "window, see Manage Center Stop Window.

      Note: If you need to delete a center point, you can select the center point and select "Remove" in the pop-up Context Menu or select the center point to be deleted and press the Delete key.

  5. In the Network Analysis Instance Management window, click the Parameter Settings "button to display Location-Allocation Parameter Settings. Set the Location-Allocation parameter.
    • Parameter Settings

      Expected number of center points: the optimal number of locations given in the Analyst Result desired by the user, so as to achieve the maximum coverage. When a Fix Center exists, the number of desired centers must not be greater than number of Fix Centers. Note: In this mode, you need to ensure that the network is fully connected.

      Least Center Mode: Select this check box to indicate that the Least Center Mode is used for analysis. In this case, the setting of the expected number of centers is invalid, and Application will calculate the minimum number of centers to cover more areas, that is, Use the least number of central points to cover the whole network, and if it can not cover the whole network, it will Analysis failed.

      . There are two possible reasons for

      Analysis failed. On the one hand, if the network is not fully connected (for example, there are isolated points or islands), Analysis failed will occur. You can check whether the network is fully connected through the flow direction: arbitrarily select a point as the source point to construct the flow direction. If the flow direction is 3, it is a disconnected position; on the other hand, there should be enough Centers and the weight (service range) should be large enough to ensure full coverage of the whole network.

      Allocate from Center: Select the check box, indicating that the allocation is performed from the central point to the request point in Location-Allocation. Otherwise, the allocation is performed from the opposite direction.

    • Result Settings

      Datasource: Select the Datasource to save the Location-Allocation result.

      Assign Point Dataset: Select this dialog box to save the analyzed assignment center point as Point Dataset and give it a name. The Tabular Dataset stores the information of the new center point, including the type of the center point, demand, weight information, etc. The following table describes the fields in the Distribution Point Center Attributes table: The amount of resources at the

      Field Explain
      CenterID Assign the Node ID.
      SupplyCenterType Assign a point type, 1 for Center; 2 for Fix Center.
      DemandCount allocation point.
      TotalWeights The total cost represents the sum of the node costs from the distribution center to all its services.
      AverageWeight Average cost, which represents the average cost of distributing the central point to each node for all its services.
      MaxWeight Assign a maximum resistance value for the center point.

      Demand Point Dataset: Select this check box to save the demand point obtained by analysis as Tabular Dataset and name it. The attribute table will store the information of all demand points, generally including all network nodes in the current network layer. The following table describes the fields in the demand point attribute table:

      Node ID of The cost path from the
      Field Explain
      CenterID demand point. When the value is -1, it indicates that the point is not a demand point.
      Cost demand point to the center point. When the value is -1, it indicates that the point is not a demand point.
      When

      Parameter Settings is complete, click OK to exit the Location-Allocation Parameter Settings dialog box.

  6. After the Parameter Settings are completed, click the Execute button in the Road Network Analysis group or in the Instance Management window to perform the analysis. The Analyst Result is displayed immediately in the Map. Analyst Results can be Save as Dataset for use elsewhere.

Precautions

  • Location Center Type must be Center or Fixed Center, otherwise Analysis failed.
  • The center point for Location-Allocation must be on a node in the network, otherwise there is no way to add it to the network layer.
  • If obstructing points are set in a Network Analysis layer, the obstructing point information is displayed in the Network Analysis management window, and the obstructing points can be managed in this window. Refer to the Barrier point management for instructions on how to add obstacle points.

Related topics

Location-Allocation Overview