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I have two separate shape files with point data. One is POI data and the other is exit location. The poi data contains the unique exit id linking it to the exit. How do I visually show this in qgis? Some exits have multiple poi's some have none.

I've tried Points2one but it only links a few of them and it seems pretty limited.

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    How many points are we talking about here? Can you label the POIs with the exit number? Do you want to somehow differentiate them with symbology? I'm not really sure what you're trying to achieve. – Fezter Aug 25 '16 at 0:54
  • You could create a straight line in another feature class (layer) but that would require some understanding of pyQGIS, avoiding obstructions between by bending the line is complex - something I'd not like to try in python... apart from that I'm not entirely sure what you're asking, can you clarify what you're trying to achieve here please. – Michael Stimson Aug 25 '16 at 4:20
  • Symbolize the POIs by Exit Number. Put that into your legend. – jbalk Aug 25 '16 at 6:02
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    It's 1400 poi points. The exits have exit number, highway number, etc. They are all across the US though so those repeat from state to state. Each exit has a unique identifier that is also included in the poi information in order to link them. I figured out how to get Points2One to work somewhat. The points you want joined have to be sorted so they follow each other on the table. I was able to get one line connecting all associated points however it would be better represented as a child/parent where each poi would have a line connecting to the exit it's associated with. – brink Aug 26 '16 at 16:16
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Using QGIS 3.0 Geometry by expression function (in Vector geometry group).

Please see a sample of two point layers (POI and EXIT).

Note that first three points in POI (id=1, 2, 3) are all linked to Exit_DEF in EXIT layer.

enter image description here

Activate Geometry by expression tool and select POI as Input layer, set Output geometry type to Line, then click on the big epsilon mark. Input an expression as below:

make_line($geometry, geometry(get_feature('EXIT', 'exit_name', "exit_id")))

enter image description here

Output would be a new Modified geometry layer:

enter image description here

  • Awesome. This looks fairly simple. I solved the problem but it was a one off thing and I don't even remember how I did it. Thanks for the response though. – brink May 8 '18 at 18:29

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