Pitney Bowes MapInfo Professional - Manual (Page 434)

districts, all the while doing calculations of the attached data on the fly for instant analysis and
decision-making.
What is Redistricting and How Can I Use It?
Redistricting is the process of assigning map objects to groups. As you assign map objects to groups,
MapInfo Professional automatically calculates totals for each group of objects, and displays the totals
in a special Browser window called the Districts Browser. This process is sometimes known as
load-balancing.
When you perform redistricting, you create a number of districts. The exact number of districts needed
depends on the nature of your work. You can assign a unique name to each district; thus, if you want to
work with four districts, you might call the districts Northeast, Southeast, Northwest, and Southwest.
Each district appears as one row in the Districts Browser.
The Districts Browser is different from other Browser windows in several respects:
• You only can select one row at a time from the Districts Browser. You cannot Shift-click to select
multiple rows.
• The Districts Browser always has one row selected; you cannot cancel the selection of this row by
choosing Unselect All.
• When you select a row from the Districts Browser, that row becomes the target district. The target
district is the district that will be affected by subsequent redistricting operations.
Once you have selected a target district, you assign map objects to that district by selecting the map
objects. You can select objects by pointing and clicking, or by performing queries such as SQL Select.
When you select map objects, MapInfo Professional tentatively assigns the selected objects to the target
district. MapInfo Professional then recalculates the totals for each district, and displays the new totals
in the Districts Browser. You can then examine the contents of the Districts Browser to decide whether
you want to make the district assignments permanent.
To cancel the tentative district assignment, cancel the selection of the map objects.
To make the tentative district assignment permanent, choose Redistrict > Assign Selected Objects.
When you choose Assign Selected Objects, MapInfo Professional stores the target district's name in the
rows of the selected objects. Thus, if you assign map objects to a district called Northwest, MapInfo
Professional stores Northwest in each object's row.
Each district has its own set of fill, line, and symbol styles. When you assign a map object to a district,
the object subsequently appears in the style of the district. Thus, if you choose a solid blue fill for the
Northeast district, objects that you assign to Northeast appear in solid blue.
For example, if you have a layer of states, you might want to combine the state boundaries to create
sales territories. Each state record includes a field, TOT_SALES, which contains the total sales for the
previous year. You would ultimately like to sum up the TOT_SALES field for each state in a given sales
territory. Redistricting is gives you the tools for creating the sales territory and combining those
TOT_SALES fields from each state's data into one table.
MapInfo Professional 12.5 434
Redistricting-Grouping Map Objects into Districts