Grouping Objects using Multipoint and Collection Object Types - MapInfo_Pro - 2023

The Multipoint and Collection object types allow you to group multiple objects into a single object. One way to create multipoints and collections is by using a Combine command (on the SPATIAL tab, in the Edit group, click Combine, and Combine Selected Objects or Combine Using Column). These object types aid in the translation and live access of other GIS data formats, such as ArcView Shape Files, and are more compatible with GIS standards. This is particularly useful for sharing maps with others using different software.

A Multipoint object consists of a number of points that have been grouped into a single object. The Multipoint object displays in a Browser window as a single record, and all the points within the object have the same symbol. One method you can use to create a multipoint object is to select a group of point objects and combine them.

A Collection object consists of multipoint objects, zero or one polyline objects, and zero or one region objects that have been grouped into a single object.

MapInfo Pro automatically converts homogeneous Collection objects to a more specific type, for example, a Collection object that contains only polylines is automatically converted to a multi-polyline object.

To create a Multipoint or Collection object using a Combine command:

1. Make the layer that you are going to select from editable if it is not already.
2. Select the objects you want to combine.
3. On the SPATIAL tab, in the Edit group, click Combine, and Combine Selected Objects to open the Data Aggregation dialog box.
   Note: Text objects cannot be used as input in a Combine operation.
4. Select the column(s) that you want to use in the aggregation and an aggregation method.
5. Click OK. The objects are combined into a single object.

   Any point objects selected are combined to form a multipoint object. Any polyline objects selected are combined to form a a new region object. The resulting multipoint (if one exists), polyline (if one exists) and region (if one exists) are grouped together to form a new collection object.

For an existing multipoint or collection object, you may need to change its styles or view the bounds information. To do so, either double-click the object, or right-click the object to display the shortcut menu and choose Get Info to open the Object Info dialog box for the selected object. If the object is not editable, the controls in the Object Info dialog box are read only.

In multipoint objects, you can change the style of the symbol that represents the multipoint. Click the Style button to open the Symbol Style dialog box.

In a collection object, you can change the styles of the different object types in your collection. Click the corresponding Style button for each object type you want to change.

Combining Objects with Multipoint and Collection Objects

The Combine commands makes use of the Multipoint and Collection object types. You can use Points, Multipoints, and Collections as input in a Combine operation.

In addition, heterogeneous combines are possible using any combination of input objects, including Multipoints and Collections.

The result of such a Combine is a Collection object.

Multipoint Objects

If you are combining point or Multipoint objects, the Combine operation produces a single Multipoint object comprising all input points. Combining points is similar to other Combine operations in that the symbol style of the resulting object is the same as that of the first object to be combined. This object is normally the first object, in row order, of the table being combined.

Specifying Multipoint Object Attributes

A multipoint object is the result of combining points into a single object. The multipoint object must be editable (reside in an editable layer) before you can specify attributes.

1. Make the table containing the multipoint object editable.
2. Do one of the following:
   • Select a multipoint object and press F7 to open the Multipoint Object dialog box.
   • Double-click the MultiPoint object to open the Multipoint Object dialog box.
3. Specify attributes for the multipoint object.
4. Click OK.

Collection Objects

The result of a Combine operation that uses heterogeneous object types as input is a Collection object. The input objects of a Collection object can be a mix of any of the following:

• Point or multipoint objects (zero-dimensional)
• Linear objects - lines, polylines, and arcs (one-dimensional)
• Closed objects - regions, rectangles, rounded rectangles, and ellipses (two-dimensional)
• Collection objects

Heterogeneous Combine operations take place in stages. First, all objects of the same dimension are combined separately. The Combine operations are done in the following manner:

• All point and Multipoint objects, as well as the Multipoint component of any Collection object in the input are combined into a new Multipoint object.
• All line, polyline, and arc objects, as well as the polyline component of any Collection objects in the input are combined into a new polyline object.
• All regions, rectangles, rounded rectangles, and ellipses, as well as the region component of any Collection objects in the input are combined into a new region object.

The resulting Multipoint, polyline, and/or region objects are then assembled into a new Collection object.

The styles for the new Collection object are derived from the styles of the separate Combine operations. These styles are assigned according to the style of the first object, in row order, of the table being combined. Keep in mind that the row order of an object may have nothing to do with the order in which you selected the objects for the Collection.

For example, the style of a Multipoint component of a Collection object is the style of the first point, Multipoint, or Multipoint component of a Collection encountered in row order. The style of a polyline component of a Collection object is the style of the first linear object or polyline component of a Collection encountered in row order. The style of a region component of a Collection object is the style of the first closed object or the region component of a Collection encountered in the input, in row order.