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I would like to split a line with a smaller line on QGIS in order to have the rest. I used split line with line but it doesn't work.

Sorry I have difficultes to explain because I'm not an English speaker. I have a big line and a smaller line which are on the space. I would to have the subtraction of them. I would like to split lines in a layer with lines in another layer using processing tools. When I try I only have the full segment as a result and not the subtraction of both

This is the bigger line : enter image description here

This is the smaller line : enter image description here

I would like the subtraction (the red circle) of them (in yellow it's still the bigger line and in green it's still the smaller line)

enter image description here

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    Welcome to GIS SE. As a new user, please take the Tour, which explains how our "Focused question / Best answer" database compilation effort operates. "It doesn't work" is not a description that is going to generate useful responses. You need to describe exactly what inputs you used and the exact result, and how that didn't meet your expectations. – Vince Apr 7 '18 at 16:24
  • Do you mean "split one line with just one line manually" or "split lines in a layer with lines in another layer using Processing tools"? If you do not ask in more detail, It's possible not to get useful answer or users will have to ask questions like that. – Kadir Şahbaz Apr 7 '18 at 16:39
  • Sorry i have difficultes to explain because I'm not an english speaker. I have a big line and a smaller line which are on the space. I would to have the soustraction of them. I would like to split lines in a layer with lines in another layer using processing tools. When I try I only have the full segment as a result and not the soustraction of both. – Joker Apr 7 '18 at 21:23
  • It wil be nice to add screenshot(s) about your problem. – Kadir Şahbaz Apr 7 '18 at 21:55
  • If I am understanding you correctly, can you use a clip tool to capture the segments that are not overlaid. this will output a new feature class/shape file displaying all line segments that previsouly did not overlay. use the big line feature as input feature and the smaller lines as the clip feature – NULL.Dude Apr 8 '18 at 20:37
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If we have the Longer line and the Shorter line on separate layers like below,

enter image description here

(1) Create a buffer around the Shorter line, by Buffer tool (QGIS 3.0 - Processing Toolbox | Vector geometry | Buffer / QGIS 2.18 - Processing Toolbox | QGIS geoalgorithms | Vector geometry tools | Fixed distance buffer)

enter image description here

(2) Cut the Longer line by the buffer. We can use Difference tool (QGIS 3.0 - Processing Toolbox | Vector overlay | Difference / QGIS 2.18 - Processing Toolbox | QGIS geoalgorithms | Vector overlay tools | Difference)

enter image description here

If the Longer and the Shorter lines are on the same layer, you will need to select the Shorter line and use Selected features only option. After that, the Step(2) is the same as the above.

  • These are the results : The tool split line with line work but doest't give the same result all the time... The buffer idea with the difference tool work even if it's a problem when you have perpendicular line with the buffer. The buffer with the symmetrical difference work but it let the contour of the buffer. – Joker Apr 14 '18 at 15:07

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