Pitney Bowes
MapInfo Pro™ Monthly Journal

Redistricting - A Hidden Feature in MapInfo Professional®

THE REDISTRICTING TOOL BUILT INTO MAPINFO PROFESSIONAL® IS A BENEFICIAL FUNCTION-AND A TOOL THAT MANY USERS MAY NOT REALIZE IS AVAILABLE.

The redistricting tool allows map objects to be assigned into groups. One example of when this may be useful is when grouping regions into sales regions or territories-a particularly useful tool for users working in a number of industries, as sales allocation is a common task.

This function allows the user to start with a boundary layer of postcodes or ZIP codes and then allocate each area to a sales region. Using the MapInfo Professional redistricting tool is a tremendous way to automate this manual, repetitive task. Also, by using the tool, users gain the advantage of their data being dynamically updated while the redistricting is being undertaken, allowing users to run what-if scenarios before a final allocation is made. The best way to understand the redistricting process is to see it in action.

In the following case, we will use an example for an audio-visual retailer looking to create store catchment areas for a network of store locations. There is a boundary layer containing a field for the dealer region and another field for the projected total expenditure for audio visual goods in 2017. The expenditure data will be particularly useful because regions need to be balanced to ensure an equal distribution of potential expenditure for each dealer region. We will use the redistricting tool to allocate or assign boundaries to our dealer regions. (figure 1)

starting map
Figure 1: Map data includes Microsoft Bing Roads and Pitney Bowes Software Expenditure Data. The Expenditure data is produced in partnership with Oxford Economics.

To initiate a new redistricting session, simply use the Window > New Redistrict Window function. The user is prompted to define which layer will be the base layer for the redistricting, as well as the field within this layer that will hold this information. Lastly, there is an option to include additional information in our Redistrict Browser; this easy access to information contained in the browser helps users make decisions about allocating sales regions. For our purposes here, we will use the population field. MapInfo Professional will generate grouped values using this numeric field (i.e., sum, percentage).
(figure 2)

window
Figure 2: Setting up a Redistricter session

Once this information is set, MapInfo Professional automatically creates a thematic layer to visually show the current allocation of regions. This layer is dynamically updated to reflect any changes in object allocation enabling the user to see and understand the effect of potential allocation before a final decision is made. Also created at this stage is a Districts Browser, which provides the user with a tabular representation of region allocation.
(figure 3)

map
Figure 3. Redistricter session in progress.

With the redistricting session initiated, we can use our standard range of selection tools (polygon select, radius select, etc.) within MapInfo Professional to select and allocate new regions. Initially, we must set our Target Region by simply selecting the appropriate region and then pressing the Set Target District button on the main toolbar, shown in the illustration below. (figure 4)

toolbar
Figure 4. These two redistricter buttons are on the Main toolbar.

Now, simply select new regions to be assigned to our Target District. As each region is selected, the Districts Browser window will be dynamically updated to reflect the change in allocation of the different regions. Multiple regions can be selected at once by simply holding down the shift key. (figure 5)

selection
Figure 5. A new district called Bradford has been created. A number of regions have been selected and are temporarily assigned to this new District.

When you have decided on your selection, click the Assign Selected Objects button on the main toolbar (shown below in figure 4) to permanently assign these objects to the selected region. These commands are also available by right-clicking within the Districts Browser. (figure 6)

assigned
Figure 6. The regions selected in the previous screen shot have now been assigned to into the District.

This process can be repeated until all region objects have been assigned to a given sales region. Alternatively, regions can easily be reassigned at any time by repeating the process. When the redistricting session is complete, save the changes (File > Save) and close the Districts Browser to return MapInfo Professional to a normal mode of operation.

Using the redistricting tool allowed us to allocate objects (in this case postal boundaries) to sales regions, providing rapid visualization of this information. In addition, with sales regions now created within MapInfo Professional, they can be easily reused for additional tasks, such as analysis of sales figures, sales forecasting/modeling and risk analysis.

The redistricting tool also allows use of point and line objects during redistricting. Other tasks-such as school or voter district allocation, delivery route allocation and dealer allocation -benefit from the use of MapInfo Professional's redistricting tool.

For more information on redistricting, refer to the MapInfo Professional User's Guide. The User Guide is available from our Web site here.

Article by Ashley Crane

When not writing articles for the MapInfo Professional journal, Ashley enjoys hearing about how Pitney Bowes customers are using our solutions to solve real world business problems and is on a journey to make & consume the perfect cup of coffee.