Re: [jts-dev] Remove line from within another line

[Martin Davis <mtnclimb@xxxxxxxxx>]

Simon,

The main problem here is that the smaller line (B) has different precision to the larger line (A).  So precisely speaking they are different geometries, and "removing B from A" actually has no meaning.  Accordingly, there is no function in JTS to "remove B from A".  

What can be done is to snap B to A, or alternatively reduce B's precision to match that of A.  If this is done then Geometry.different() can be used to carry out the desired operation.

On Sun, Oct 7, 2018 at 2:51 PM Simon (SPDBA) Greener <simon@xxxxxxxxxxxx> wrote:

JTSers,

Perhaps I am not seeing how I should use JTS to answer my question, so I 
thought I would ask.

I have a LinearRing as follows:

LINESTRING (548845.37 3956342.94, 548840.24 3956243.07, 548861.63 
3956241.98, 548881.28 3956242.9, 548900.36 3956247.66, 548918.14 
3956256.06, 548933.94 3956267.77, 548947.13 3956282.36, 548957.22 
3956299.24, 548963.81 3956317.77, 548966.65 3956337.23, 548965.62 
3956356.87, 548960.77 3956375.93, 548952.28 3956393.67, 548940.48 
3956409.4, 548925.83 3956422.53, 548825.48 3956496.01, 548766.4 
3956415.33, 548866.75 3956341.84, 548845.37 3956342.94)

 From which I wish to remove the following LineString:

LINESTRING (548845.366 3956342.941, 548866.753 3956341.844, 548766.398 
3956415.329)

I have tried using ST_LineDissolver but am not getting the resultant 
linestring back.

The solution needs to be robust in that the LinearRing could have 
different orientation than the LineString.

Any suggestions?

Regards
Simon
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