Opened 6 years ago
Closed 6 years ago
#400 closed defect (fixed)
ST_Split
Reported by: | strk | Owned by: | strk |
---|---|---|---|
Priority: | medium | Milestone: | PostGIS 2.0.0 |
Component: | postgis | Version: | |
Keywords: | Cc: |
Description
Split polygon by line, line by line, line by point. Returns components as either a set or collection.
Change History (6)
comment:1 Changed 6 years ago by strk
comment:2 Changed 6 years ago by strk
Alright, here's the contract:
- Will split a poly by a line, a line by a line and a line by a point
- Will always return a COLLECTION of at most 2 elements: first element is what is left after the cut, second element is what was cut
- When you cut a line using a point, what's left is the initial portion of the line (from start to point)
- When you cut a poly or a line using a line what's left is arbitrarly taken as the cut-part which goes to the *left* of the cut line. This is for assonance with the word "left"
For now there's no support for multi-part geometries requiring cutting, but given this contract it might not be too hard to support (every non-cut geometry would go to the "left" part).
comment:3 Changed 6 years ago by strk
- Status changed from new to assigned
Again, trying to have trac keep my formatting :/
- Will split a poly by a line, a line by a line and a line by a point - Will always return a COLLECTION of at most 2 elements: first element is what is left after the cut, second element is what was cut - When you cut a line using a point, what's left is the initial portion of the line (from start to point) - When you cut a poly or a line using a line what's left is arbitrarly taken as the cut-part which goes to the *left* of the cut line. This is for assonance with the word "left"
comment:4 Changed 6 years ago by strk
Come again (sorry, but can't sleep till I succeed in getting it formatted right)
- Will split a poly by a line, a line by a line and a line by a point
- Will always return a COLLECTION of at most 2 elements: first element is what is left after the cut, second element is what was cut
- When you cut a line using a point, what's left is the initial portion of the line (from start to point)
- When you cut a poly or a line using a line what's left is arbitrarly taken as the cut-part which goes to the *left* of the cut line. This is for assonance with the word "left"
Thanks paul if this works :)
comment:5 Changed 6 years ago by strk
- Summary changed from ST_SplitGeometry to ST_Split
Contract changed. We always return a collection but of as many elements as required to represent all components of output.
Currently line-by-point, line-by-line and poly-by-line splitting are supported and the function name is ST_Split.
Unsupported are all MULTI* and GEOMETRYCOLLECTION, but I'd like to add support for them too. The use case I have in mind is in conjunction to the ST_WrapX function proposed in ticket #454 (still not convinced about that function name:)
comment:6 Changed 6 years ago by strk
- Resolution set to fixed
- Status changed from assigned to closed
As of r5444 multi* and collections are also supported. Documentation and testcases are in place.
Ideas for the area/line case: http://trac.osgeo.org/postgis/wiki/UsersWikiSplitPolygonWithLineString