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Manipulating Sets


The Selection toolbar and Selection Settings dialog box can be used to modify the appearance of a selection set, to rename a selection set, and to delete it. These operations are described on the main Selection Sets page.

It is also possible to manipulate selection sets by combining them using the Combine Selection dialog box. This is displayed by selecting Selection->Combine Selection on the main menu:

The Combine Selection dialog box

The Combine Selection dialog box

This creates a new selection set (Selection in the above example) from one or two selection sets (Adjacent2 and Adjacent1 in the above example). A total of seven different operations are possible:

  • Copying: Copy all features from the input selection set
  • Choosing all features: Select all features in the layer
  • Choosing features not in: Selects all features that are NOT in the input selection set (“complement”)
  • Choosing features in both: Selects all features in both of the input selection sets (“intersection”)
  • Choosing features in either: Selects features that are in either of the input selection sets (“union”)
  • Choosing features in one: Selects features in one (but not both) selection sets (“exclusive or”)
  • Removing features in: Removes all features in set 1 from set 2

These operations allow for set algebra and the combination of different queries. For example “Which residential lots are more than 1/4 acre and within 2 miles of a school?” or “Which zipcodes have a population greater than 10,000 and have not seen any reported disease outbreaks?”

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