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https://issues.apache.org/jira/browse/GEOMETRY-146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17519538#comment-17519538
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Matt Juntunen commented on GEOMETRY-146:
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{quote}From this assumption, I'd suggest that the class name reflects its
importance, similarly to the "Navigable" qualifier in the [JDK
{{NavigableMap}}|https://docs.oracle.com/javase/8/docs/api/java/util/NavigableMap.html].
{quote}
It is part of the class name: {{DistanceOrdering}}, which is returned from
several of the methods in my proposed API.
bq. In this case, there may be no reason; but we could imagine another selector
where some part of the computation is performed at instantiation and should not
be repeated for each point.
Yes. I would imagine a separate method in the API for that.
{quote}Could selectors be defined as
class PointMap<P, V> {
public interface Selector<P, V> extends Function<PointMap<P, V>, P> {};
}
?
{quote}
Do you mean
{code:java}
interface Selector<P, V> extends Function<P, PointMap<P, V>> {}
{code}
?
In other words, the selector accepts a point and returns a {{PointMap}} view?
There are 2 issues with this:
- This presupposes that the only selection criteria to be used will be a point,
which may not be the case. For example, what if we wanted to select points with
a bounding box? That would not fit this interface.
- Returning another full {{PointMap}} instance as a view of the main map is not
feasible at this point. Doing so would be very complicated with the current
algorithms and I don't believe it would have much use either.
bq. Can the "sub-map" be a "view" of the same data-structure?
That's what I have implemented. {{DistanceOrdering}} is a view of the
underlying {{PointMap/Set}}. It is accessed through selection methods (e.g.
{{PointMap.entriesWithinDistance(P, double)}}), similar to {{Map.entrySet()}}.
{quote}
Given a point "p" of type P, are the 2 iterators (over all points in the
PointMap instance):
in increasing distance from "p"
in decreasing distance
"naturally" (efficiently) defined?
{quote}
Yes.
It would be helpful to me if you could respond to my latest API proposal from
Mar 30. I feel like this both meets some of the requirements that you are
mentioning as well as being similar to the approaches used in {{java.util.Map}}.
> PointSet/Map closest points
> ---------------------------
>
> Key: GEOMETRY-146
> URL: https://issues.apache.org/jira/browse/GEOMETRY-146
> Project: Commons Geometry
> Issue Type: New Feature
> Reporter: Matt Juntunen
> Priority: Major
> Fix For: 1.1
>
>
> Add methods to the new {{PointSet}} and {{PointMap}} interfaces to allow
> querying of points in order of distance from a query point.
> {code:java}
> PointSet<P> {
> // find the closest point to pt or null if empty
> P closest(P pt);
> // iterate through points in order, with points closest to pt coming first
> Iterable<P> closestFirst(P pt);
> // find the farthest point from pt or null if emtpy
> P farthest(P pt);
> // iterate through point in order, with points farthest from pt coming
> first
> Iterable<P> farthestFirst(P pt);
> }
> {code}
> {{PointMap}} should have similar methods providing access to the map keys and
> entries.
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