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I have 2 linestrings: Linestring 1 (-3 3, 6 8, 15 9, 22 13, 28.5 15.7) --> red color Linestring 2 (0 4.66666666666667, 6 8, 10 8.44444444444444) --> blue color

Actually both two linestrings are coincident

enter image description here

How do I get a part of linestring 1(red) that are not coincident with linestring 2 (blue) in PostGIS (as a multilinestring) ?

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  • Welcome to GSE. Please perform the due diligence of reviewing the documentation on spatial operators before posting questions for which a one line answer is appropriate.
    – Vince
    Dec 13, 2014 at 19:32

1 Answer 1

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I think ST_Difference is what you are looking for.

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  • No, the result is wrong, because there are some points in linestring 2 (blue) that are not part of linestring 1 (red). I have tried using both st_difference and st_symdifference, but the results are wrong
    – doel
    Dec 14, 2014 at 11:45
  • I mean that there are some points in linestring 2 (blue) that are no the vertexs of linestring 1 (red).
    – doel
    Dec 14, 2014 at 11:54
  • Perhaps you could state what output you expect, as ST_Difference answers your question as stated. Dec 15, 2014 at 6:16
  • the output I expect is a multi linestring: fist part of red linestring, and the second part of red linestring -> multilinestring((-3 3,0.466667),(10 8.4444,15 9,22 13,28.5 15.7))
    – doel
    Dec 15, 2014 at 6:47

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