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map

In the image you can see districts in BLUE with attributes (name of district) and small pieces in RED. The red polygons belong to the blue and I want to merge them. The RED are only towards the outside and never surrounded by BLUE.

How can I add/merge/union/eliminate the RED with the nearest/closest/longest-sharing-border of a BLUE.

I am using ArcMAP 10.2 on Win7 and I have tried the Eliminate Tool but that does not give the desired result, because the area of the RED is sometimes larger and would absorb a nearby BLUE = attributes are lost. Also small BLUE districts surrounded by other BLUE are getting merged = attributes and shape are lost.

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You should still be able to accomplish this using the Eliminate command.

Instead of just running the stock Eliminate, use the "Exclusion Expression" to select all of the Blue polygons based upon an expression. For example, if all Blue have a [NAME] attribute populated, and the RED are blank, then just SELECT * FROM LAYER WHERE [NAME] IS NOT NULL.

If there are no fields that differentiate the RED from BLUE, just create a new one.

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  • Hey, thanks for that! I have tried it and the result is that the RED get merged together, but not with a BLUE.
    – Michael
    Nov 15, 2013 at 18:20
  • Have you tried testing both of the selection options? Maybe AREA will work better then LENGTH. Based upon the images you show above, area should work (although I would have guessed LENGTH would have worked, too). You could also iterate the function multiple times until you no longer have any RED polygons.
    – RyanKDalton
    Nov 15, 2013 at 18:26
  • Finally i came up with another method to achieve this task. Eliminate does not do what I want to accomplish.
    – Michael
    Dec 2, 2013 at 10:40
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    @Michael, please leave an "Answer" below and let others know what method you went with so that others can learn from your experience. Then, after you have posted your answer, please mark it as "Accepted" (it is OK to accept your own answer if you figured it our yourself). You may have to wait a couple of days until you can accept your own answer.
    – RyanKDalton
    Dec 2, 2013 at 15:26
  • I have used an entirely different approach of converting all blue polygons to lines. Then i deleted the outer line (coastline) to find dangles (vertices with only one node). From these points i made a shortest line to the real outer boundary (which also covers the red polygons). From there it is a easy task to get all lines back to polygons.
    – Michael
    Dec 10, 2013 at 8:56

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