11

I created voronoi polygons after which I dissolved them on the basis of one attribute. Now there are cases where in for one single attribute "abc" I have3 polygons at different places with same object id. I would like to break these into 3 polygons as they are at different locations.

Is there any tool in ArcGIS Desktop or QGIS which can help me in doing that?

24

I think that what you actually want to do is to convert multipart polygons into singlepart polygons.

In ArcGIS it can be done using Multipart To Singlepart (Data Management) tool.

22

In QGIS vector menu, as well as in the Processing Toolbox, you'll find Multipart To Singlepart.

This algorithm takes a vector layer with multipart geometries and generates a new one in which all geometries contain a single part. Features with multipart geometries are divided in as many different features as parts the geometry contain, and the same attributes are used for each of them.

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8

You should specify option SINGLE_PART when running ArcGIS Dissolve tool:

SINGLE_PART —Specifies multipart features are not allowed. Instead of creating multipart features, individual features will be created for each part.

  • As Alex said, there is an option/check box in Arcgis 9.3 Dissolve tool, - "Create multipart features", it is "checked" as default. – vadivelan Jun 20 '12 at 15:29
  • 2
    This is the best answer for preventing the problem when using ArcGIS. The Multipart To Singlepart tool (referenced by Marcin) is the best way to fix the issue after-the-fact. – user3461 Jun 21 '12 at 11:54
3

Another Less elegant option is to click the Explode button in Advanced Editing toolbar in Arcgis after selecting all features in Layer.

0

A suggestion for all you R enthusiasts or new learners (like myself) out there: The same thing can be achieved in R with the disaggregate function from the sp library.

output <- disaggregate(input)

Simple as that.

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