Enhancement: containsVertex function

[mtnclimb]

A containsVertex function might be a useful addition.

int containsVertex(Geometry geom, double x, double y)

I geom contains a vertex with location (x,y), returns the index of that vertex. Otherwise returns -1. For geometrys which contain more than one coordinate sequence, the index is the cumulative index over all coordinate sequences.

This can be implemented as a fast linear scan of all vertices in the geometry.

[kneufeld]

Agreed, esp. if one is doing linear referencing or edit a single point in a geometry.

or int ST_ContainsPoint(Geometry geom, Geometry point) or int ST_ContainsCoordinate(Geometry geom, Geometry point)

Though I think the cumulative index part could get confusing. We could restrict the use to LineStrings only.

[pramsey]

What about multi-line strings? Behavior?

[mtnclimb]

One idea is to use the cumulative index idea. So for a ML:

g = MULTILINESTRING((0 0, 1 1) (1 1, 2 2))

ST_ContainsPoint(g, pt(0,0)) = 0 ST_ContainsPoint(g, pt(1,1)) = 1 1st one found is returned ST_ContainsPoint(g, pt(2,2)) = 3 2nd linestring has indexes 2, 3

Another is to return a pair (lineIndex, ptIndex) - but this might make for more complicated code in the caller.

[kneufeld]

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[pramsey]

Two year old, no movement, retiring until someone decides to love this ticket.