6

I have a multilinestring made up of several pieces, some of which are facing the wrong direction. (Accessible here: http://pastebin.com/89Zcixv5 )

I think what I'm looking for is some utilization of ST_MakeLine, but when I try to use it, the pieces of the trail get put together wrong. (See: http://i5.minus.com/iJ5QVbaA9rm2g.png )

enter image description here

I have a ton of trails in this format that I need to convert from MultiLineStrings to LineStrings containing the whole trail.

If anybody has any ideas, I'd greatly appreciate all the help I can get!

Thanks!

  • What format are those LineString points in your pastebin? – Caio Iglesias Jun 16 '16 at 0:49
3

Easy, use ST_LineMerge with the MultiLineString geometry.

SELECT ST_LineMerge(geom) FROM ...

Returns a LineString if it is possible, such is the example in the question.

ST_LineMerge

0

looking from picture. Valid linestring cannot touch itself. So picture data should could create 3+ linestring.

You can use ST_Dump to dump multi in order which it has been created. Then you can try use st_linemerge until you get multiline. One solution is use st_StartPoint and st_endpoint comparison to linestrings and use st_reverse if needed.(end=end || start=start)

  • 1
    A code example would be helpful to show how to accomplish this – clhenrick May 5 '17 at 1:08

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