| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.geometry.core; |
| |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.stream.Collectors; |
| |
| /** This interface defines mappings between a space and one of its subspaces. |
| |
| * <p>Subspaces are the lower-dimension subsets of a space. For example, |
| * in an n-dimension space, the subspaces are the (n-1) dimension space, |
| * the (n-2) dimension space, and so on. This interface can be used regardless |
| * of the difference in number of dimensions between the space and the target |
| * subspace. For example, a line in 3D Euclidean space can use this interface |
| * to map directly from 3D Euclidean space to 1D Euclidean space (ie, the location |
| * along the line).</p> |
| * |
| * @param <P> Point type defining the embedding space. |
| * @param <S> Point type defining the embedded subspace. |
| */ |
| public interface Embedding<P extends Point<P>, S extends Point<S>> { |
| |
| /** Transform a space point into a subspace point. |
| * @param point n-dimension point of the space |
| * @return lower-dimension point of the subspace corresponding to |
| * the specified space point |
| * @see #toSpace |
| */ |
| S toSubspace(P point); |
| |
| /** Transform a collection of space points into subspace points. |
| * @param points collection of n-dimension points to transform |
| * @return collection of transformed lower-dimension points. |
| * @see #toSubspace(Point) |
| */ |
| default List<S> toSubspace(final Collection<P> points) { |
| return points.stream().map(this::toSubspace).collect(Collectors.toList()); |
| } |
| |
| /** Transform a subspace point into a space point. |
| * @param point lower-dimension point of the subspace |
| * @return n-dimension point of the space corresponding to the |
| * specified subspace point |
| * @see #toSubspace(Point) |
| */ |
| P toSpace(S point); |
| |
| /** Transform a collection of subspace points into space points. |
| * @param points collection of lower-dimension points to transform |
| * @return collection of transformed n-dimension points. |
| * @see #toSpace(Point) |
| */ |
| default List<P> toSpace(final Collection<S> points) { |
| return points.stream().map(this::toSpace).collect(Collectors.toList()); |
| } |
| } |