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In QGIS 3.22.0 (Bialowieza) I have a polygon layer of municipalities in Germany. Some municipalities consist of more than one polygon. I have duplicated the layer in order to make a categorization of a value within the layer. The categorization is displayed as a point-symbol.

My problem is that the municipalities with more than one polygon also show more than one point-symbol (attached image). How can I reduce the number of points and have the point only displayed in the largest polygon. (The municipality of Konstanz consists of three polygons.)

Enter image description here

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  • What do you mean by "schon"? "show"? "already has"? Or something else?
    – Peter Mortensen
    Jun 21, 2022 at 10:26
  • oh, thank you! Its supposed to be "show".
    – rtaani
    Jun 21, 2022 at 10:29

2 Answers 2

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Have you tried to change symbol settings?

Layer Properties > Symbology > Symbol (arrow down) > Configure Symbol > Symbol layer type set on Centroid Fill.

At this point you should uncheck "Draw markers on every part of multi-part features".

enter image description here

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  • This only works for multipart geometries, not for single parts. OP mentions that some municipalities consist "of more than one polygon".
    – Babel
    Jun 20, 2022 at 16:11
  • Thank you! I knew there was a setting, just couldnt find it!
    – rtaani
    Jun 21, 2022 at 6:11
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If you want to create a marker only on the largest polygon of those with the same value for attribute name, use the Geometry generator with this expression:

if (
    area ($geometry) = 
        array_max (
            array_agg (
                area($geometry), 
                group_by:=name  --change this for the attribute field name
            )
        ),
    centroid ($geometry),
    ''
)

enter image description here

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1
  • This didnt work for my case because i had already categorized the attributes. There was no need for generating geometries (it probably could've worked, but I'm still not that professional with expressions). Thanks for your help
    – rtaani
    Jun 21, 2022 at 6:13

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