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Create by Adjacency

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It is also possible to select features according to their adjacency to selected features in the same area layer. This topological query has applications in determining territory adjacency and disease mapping.

To do this, first create a selection of the required “central” features. These are the ones that you will be testing adjacency against. In the examples below, we have selected a zipcode in central Wichita Falls,TX (it appears a salmon pink color). Next select Selection->Select by Adjacency on the main menu to display the Select by Adjacency dialog box:

The Select by Adjacency dialog box

The Select by Adjacency dialog box

Here the central features are in the Selection selection set. Enter the name for the new selection set in the Create Sets combo-box. There are a number of different adjacency methods:

  • Intersecting: Choose neighbor features that touch along edges or nodes
  • Edge: Choose features that only touch along an edge
  • Only Node: Choose features that touch only at nodes (and not edges)
  • All Nodes: Choose features that touch any nodes
  • Within: Choose features that are at least partially within a specified distance
  • Bands by Intersection: As with Intersecting but multiple concentric bands are selected (see below)
  • Bands by Edge: As with Edge but multiple concentric bands are selected

Here is an example of the Intersecting method used to select all zipcodes (cyan) adjacent to the central (salmon pink) zipcode:

Example of the Intersection Adjacency method

Example of the Intersection Adjacency method to select (cyan) zipcodes adjacent to the central (salmon pink) zipcode.

The Bands by Intersect and Bands by Edge methods can create concentric bands. For example, one band would appear as above (cyan), but a second band would feature the zipcodes adjacent to the above cyan band. Here is the dialog box set to create three bands using the Bands by Intersect method:

Select by Adjacency dialog box set to display 3 bands

Select by Adjacency dialog box set to display 3 bands

And here are the results:

Three bands. Note that Maptitude has created a separate selection set for each band.

Three bands. Note that Maptitude has created a separate selection set for each band.

 

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