Data Aggregation Dialog Box - MapInfo_Pro - 2023

There are several slightly different versions of the Data Aggregation dialog box; the dialog box that displays depends on whether you are combining or offsetting objects, have specified a map editing target, and whether the currently-selected objects are in the same table as the target.

The Combine Selected Objects command writes a row to your table; this row represents the union of the selected objects. To define the data values MapInfo Pro stores in the columns of this row, complete the Data Aggregation dialog box.

The Offset Object command also uses data aggregation to bring over values of the objects that are moved and/or copied. Only Blank and Value aggregation methods are available with Offset.

The Drivetime server also uses this dialog box to allow you to select the data aggregation options. This version of the dialog box contains a Drive Value field.

List of Columns

A list of column names appears in the upper half of the dialog box. To select one column name from the list, click on that column name. To select a group of column names, Shift-click. To select or clear one column at a time, select Ctrl-click.

Once you have selected one or more columns, click on an option in the lower half of the dialog box to apply that option to all selected columns. If you want to choose the Sum or Average method, make sure that all of the selected columns are numeric columns. If any of the selected columns are not numeric, the Sum and Average options are grayed, because Sum and Average cannot be applied to non-numeric columns.

Aggregate Method

Blank

Choose Blank to store blank values in the selected column(s). To store blank values in all columns, check the No Data check box. Only choose the Blank option when you want to blank out individual columns. The Blank option is available only if you did not specify a map editing target.

No Change

This option only displays when you combine objects into a target object. Select this option to keep the value for the selected column in the target row unchanged.

Value

The Value option is a radio button with an associated text edit field. Choose the Value option to store the value displayed in the edit field in the new row. Enter an appropriate value in the field.

Sum

Choose the Sum option to calculate a sum based on the column values from all the objects to be combined. MapInfo Pro stores the sum in a column of the new row. The Sum option is available only if you have selected a numeric column or columns. If you have specified a map editing target, and if the editing target is in a different table than the currently selected object(s), the Sum option adds numeric values from both tables, and stores the sum in a column of the target object.

Drive Value

Choose this button to place the drive value associated with the resulting buffer in the selected column.

To add values from two tables (not available for Offset or Drivetime):

1. Choose a column name from the list in the upper half of the dialog box. This choice designates which of the target object's columns hold the sum value.
2. Choose a column name other than None from the drop-down list in the lower right part of the dialog box. This drop-down list contains all numeric columns from the selected objects.
3. Choose the Sum option. MapInfo Pro calculates the sum of values of the selected objects' numeric column (the column you chose in step 2), then adds the target object's numeric column (the column you chose in step 1), and stores the grand total in the target object's numeric column.

   Average

   Choose the Average option to calculate the average of the column values for all the objects to be combined. MapInfo Pro stores the average in the new row.

   • If you choose the Average option, and you do not choose a Weight By column, MapInfo Pro calculates simple averages: MapInfo Pro sums the data values from all the objects to be combined, and divides the sum by the number of objects to be combined. If you choose a Weight By column, MapInfo Pro calculates weighted averages.

     The Average option is available if you have selected only numeric columns. Furthermore, if you have specified a map editing target, and if the editing target is in a different table than the currently selected object(s), the Average option only becomes available when you choose a column name other than none in the Columns drop-down list.

     Weight By

     Choose a column from the Weight By drop-down list to perform weighted averaging. With weighted averaging, MapInfo Pro adjusts the calculation of averages so that the values from each selected object are weighted more or less heavily. Thus, the Weight By column gives some of the selected objects more impact, or weight than others.

     For example, your table may contain two numeric columns: a median income column, med_inc, and a net population column, net_pop. When you combine two regions in this table, you probably want to use the Average option to calculate the average of the median income values. Thus, if one region has a med_inc value of $30,000, and another region has a med_inc value of $36,000, and you combine the two regions, the resultant region might have a med_inc value of $33,000.

However, if one of the regions has a larger population than the other region, you probably want the larger region's med_inc value to be weighted more heavily when MapInfo Pro calculates the average median income.

In the Data Aggregation dialog box, perform these steps:

1. Choose the med_inc column from the list in the upper part of the dialog box.
2. Choose Average. MapInfo Pro averages the med_inc values when combining objects.
3. Choose the net_pop column from the Weight By drop-down list. MapInfo Pro weights the average median income calculations. Thus, objects with large net_pop values affect the median income averaging more than objects with small net_pop values.
   • If you are combining closed objects, the Weight By drop-down list contains a special option: Area. If you choose Area from the Weight By drop-down list, MapInfo Pro weights the average calculations according to the relative geographic areas of the regions to be combined.
   • If you are combining linear objects, do not choose Area as the Weight By option. Linear objects have no width, thus they have no area.
   • To choose standard (non-weighted) averaging, choose None from the Weight By drop-down list. The Weight By control becomes available when you select the Average option. The Weight By control is not available if the target object is in a different table than the selected objects.

     No Data

     The role of the No Data check box depends on whether you have specified a map editing target.

   • If you have not specified a target, select the No Data check box to store blank values in all columns of the new row.
   • If you have specified a target, select the No Data check box to leave all column values of the target object unchanged.