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https://issues.apache.org/jira/browse/GEOMETRY-30?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16938549#comment-16938549
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Matt Juntunen commented on GEOMETRY-30:
---------------------------------------
[Here|https://github.com/darkma773r/commons-geometry/blob/geometry-32-working/commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/threed/RegionBSPTree3D.java#L654]
is an actual example from my geometry-32 working branch where I'm computing
the region barycenter. I use separate doubles for each component to avoid
unnecessary vector creation. This same type of construct is repeated in all of
the other {{RegionBSPTreeXD}} classes.
> VectorBuilder?D Classes
> -----------------------
>
> Key: GEOMETRY-30
> URL: https://issues.apache.org/jira/browse/GEOMETRY-30
> Project: Apache Commons Geometry
> Issue Type: Wish
> Reporter: Matt Juntunen
> Priority: Major
>
> We should add a {{VectorBuilder?D}} class for each dimension. These classes
> would have the same coordinate properties as their corresponding {{Vector}}
> classes but would be mutable. They would be used to build {{Vector}}
> instances from a number of input values without requiring a new instance to
> be created for each step. The primary API should look something like this:
> {code:java}
> public class VectorBuilder2D {
> double getX();
> VectorBuilder2D setX(double);
> double getY();
> VectorBuilder2D setY(double);
> VectorBuilder2D add(Vector2D);
> VectorBuilder2D subtract(Vector2D);
> VectorBuilder2D multiply(double);
> Vector2D toVector();
> }
> {code}
> A good use case for this is computing a centroid:
> {code:java}
> VectorBuilder2D builder = new VectorBuilder2D();
> for (Vector2D pt : points) {
> builder.add(pt);
> }
> builder.multiply(1.0 / points.size());
> Vector2D centroid = builder.toVector();
> {code}
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