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In QGIS 3.16. I have a shapefile (polygon) layer with an attribute table.
What I'd like to do is select certain polygon features and turn them into parts of one multipart polygon feature, without affecting the other, unselected features on my layer. If possible, I'd like to do this

  1. in a way that allows me to select which of the multiple selected features to keep the attributes from;
  2. in a way that does not create a new layer each time (I want to do this many times for my layer) but simply collapses the selected features into one line (with the chosen attributes).

If possible, though this is less important, I'd also like to do it:

  1. by physical selection (clicking) rather than grouping by attribute.

I believe that this is possible in ArcGIS, but in QGIS the existing methods of turning 'features' into 'parts of features' that I am aware of, do not allow one or more of these criteria.
For example,

  • "Collect geometries" automatically picks one feature from which to pull the attributes that it will assigned to the new, multipart feature (and it creates a new layer).
  • "Aggregate" has a range of options for determining the attributes of the new, multipart feature (collect, sum, concatenate...) but as far as I can see it does not allow simply selecting one of the source features for the totality of its attributes. (And it creates a new layer.)
  • "Promote to multipart" creates multipart geometry but does not actually turn features into parts of features.

Is there a plugin for this?

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  • Welcome to GIS SE! We're a little different from other sites; this isn't a discussion forum but a Q&A site. Your questions should as much as possible describe not just what you want to do, but precisely what you have tried and where you are stuck trying that. Please check out our short tour for more about how the site works
    – Ian Turton
    May 18, 2021 at 9:33
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    Hi and thanks Ian. My post explains 3 tools that I have tried and why they do not accomplish my goal. I think my question is precise, and I hope clear. How can I improve my post to make it more useful?
    – pete
    May 18, 2021 at 10:03

1 Answer 1

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First merge attributes, than features:

  1. Select polygons, toggle editing, click Merge Feature Attributes (screenshot 1) and select the feature with the attributes to keep, click Take attributes from selected feature, run.

  2. Clicke Merge Selected Features (screenshot 2).

Screenshot 1: merging attributes enter image description here

Screenshot 2: merging features enter image description here

Result: enter image description here

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