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I have a separate layer with polylines that are merged into one object. I want to split it by a separate layers with points in QGIS.

I have tried using the SAGA tool "Split Lines at Point" and I have tried converting the points to lines and used the tool "Split with lines" as suggested in other threads.

But I can't get the right result (as shown below) - the tools also splits the merged polyline in intersections and not just at the points.

Before splitting the merged polyline object (I only want it to be split at the points): enter image description here



After splitting the polyline object (I dont want it to split the lines marked in the red circle, but the tool also splits at these intersections): enter image description here

1 Answer 1

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I have a solution for you but its not exactly straighforward

  1. Dissolve all lines if they aren't all dissolved enter image description here

  2. Convert dissolved lines to single parts enter image description here

  3. Create all line intersections enter image description here

  4. Extract points which aren't in your starting points enter image description here

  5. Extract lines intersecting the extracted points enter image description here

  6. Extract the lines which will not be dissolved enter image description here

  7. Run the "disconnected islands" plugin on the lines supposed to be dissolved (result of step 5) enter image description here

  8. Dissolve the lines using the generated field attribute in step 7 enter image description here enter image description here

  9. Merge the results of step 8 and 6 enter image description here

Final Result: enter image description here

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