Splitting Objects allows you to divide the target object into smaller objects, using another object as a cutter. You can also combine objects into territories using redistricting. For example, you might use Split to separate a large territory into smaller units.
You can split either closed objects (regions, ellipses, rectangles, or rounded rectangles) or open objects (polylines, lines and arcs) using the Split command. You cannot use Split on points or text objects or to cut objects that are not in editable layers.
For more about the redistricting process, see Redistricting-Grouping Map Objects into Districts.
To split map objects using Set Target:
- Select the object(s) in an editable layer to be the target.
- On the SPATIAL tab, in the Edit group, click Set Target.
The object(s) displays in a different style to indicate that it is the target object.
- Select (or create and select) one or more map objects from any layer in the Map window to be the cutter object. The object must be a closed object.
- On the SPATIAL tab, in the Edit group, click Split, and Split Target to open the Data Disaggregation dialog box.
Value Edit field.
- Highlight each field and select the appropriate disaggregation method in the Destination list. Selecting the No Data check box ensures that no data is brought over for the fields. For definitions for these methods, see Aggregating and Disaggregating Data.
- Blank - Select this option to store blank values in the selected field(s). We recommend you choose the Blank option to blank out individual fields only.
- Value - Select this option to store the value that you enter in the Value Edit field in the selected field(s) of the new table.
If the table structure you are splitting from has a different table structure than the table you are saving the results to, a drop-down list displays beside the Value Edit field. This list contains the columns associated with the table you are saving the split data to.
To save the value in this field to a particular column in the new table (layer), select the column from the list.
- Area Proportion - Select this option if the field is a numeric field, to adjust the area proportion to reflect the proportion of the newly split object.
To select more then one field in this dialog box at a time:
Shift-click to apply the same method to consecutive fields
Ctrl-click for non-consecutive fields
- Click OK.
MapInfo Pro computes the new objects and displays them. Use the Info window (On the HOME tab, in the Windows group, click Tool Windows, and click Info from the list) to view the disaggregated data (if any) of the split objects. After splitting the target object(s), MapInfo Pro deletes the original target from the table. The new objects are appended to the end of the table.
Proportioning Associated Data after Using Split
After using the Split command, you may want to proportion (disaggregate) the associated data. Data disaggregation splits the data associated with a map object into smaller parts to match the new map objects. For instance, you may want to split a state into regions and have the data previously associated with the entire state proportioned for each new region. When you initiate the Split command, a Data Disaggregation dialog box opens to specify how the data will be proportioned.
Splitting Map Objects Using a Polyline
You can split multipoints and collections, as well as closed objects (regions, ellipses, rectangles, and rounded rectangles), and linear objects (polylines, lines and arcs) using the Split Target using Polyline command.
As mentioned previously, splitting objects requires that the cutter be a closed object. With Split Using Polyline, the polyline cutter will first be transformed into a region suitable for the cutter operation. The region created will be displayed for acceptance. The polyline(s) used as the cutter must be contiguous and non-branching. In general, if the cutter polylines were to be combined, the result would be a one single section polyline. If the cutters are not polylines, and are not contiguous and non-branching, then an error will occur, and the operation will be cancelled.
To split a map object:
- Make the target table editable.
- Select the object(s) to be used as targets for editing using the selection commands or the SQL Select command located on the SPATIAL tab in the Selection group.
- Set the objects as targets using the Set Target command, or by using the MapBasic Set Target On statement.
- Create the cutting object(s) (or use objects from the same or different layer). The cutter object(s) must be contiguous, non-branching polylines.
- Select the cutting object.
- On the SPATIAL tab, in the Edit group, click Split, and Split Target using Polyline.
- A region object is created from the polyline to be used as the cutter object.
Note: Only objects that intersect the original polyline will remain as targets. Some objects may be removed from the list of target objects.
- Click Next to open the Data Disaggregation dialog box.
Data disaggregation splits the data associated with a map object into smaller parts to match the new map objects. For example, you may want to split a state into regions and have the data previously associated with the entire state proportioned for each new region. Complete the Data Disaggregation dialog box.
- Click OK.
The target object(s) will be split into smaller map objects.
After splitting the target object(s), MapInfo Pro deletes the original target from the table. The new objects are appended to the end of the table.