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Is there a way to get line segments from a linestring using points with lat/lng coordinates?

ST_Line_Substring is taking float8 start/end points. Is there a way to replace the float8 with lat/lng? I have also seen ST_pointN but I have random points that are not the same as the linestrng edges. ST_Split is useful but I need to install postgis 2.0 and that will require a configuration of my whole system which is in my plan but not yet..

Regards, A

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  • Do you want to move or snap a Lines Vertices to other Points? Or do you want to create a New LineString from points that are close to your existing LineString? I don't fully understand your question.
    – klewis
    Dec 29, 2011 at 17:22
  • Is this what you are trying to do? Going from left to right, take a linestring, give points on the linesting and return the the all the points in between?
    – Nate
    Dec 29, 2011 at 17:35
  • I 'll explain step by step. I am buffering a polygon and getting its boundary which returns a linestring in which the start and end are the same point. Then, I have random points on the buffered linestring and I want to use them to cut the linestring into pieces. I have written down methods that involve st_split or st_dumppoints but these functions are all in other postgis versions. I hope this makes sense. THX!
    – Antony
    Dec 30, 2011 at 10:13
  • Which version of postgis are you using st_dumppoints has existed since 1.5. ST_SPlit is new in upcoming PostGIS 2.0
    – Regina Obe
    Jan 15, 2012 at 4:33
  • hi, i am now usign 1.5 but i will definatelly install 2.0 once it gets a bit more stable. Anyway, what I did to solve this issue was to get the npoint count and create a dictionary in my code with vertex id as key and point geom as value. I could then use postgis 1.3 functions to come around my problem. Of course when 2.0 is installed, i will be able to greatly optimise my code :)
    – Antony
    Jan 16, 2012 at 12:02

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