org.apache.commons.geometry.core.Embedding Maven / Gradle / Ivy
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/*
* 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.
* 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).
*
* @param Point type defining the embedding space.
* @param Point type defining the embedded subspace.
*/
public interface Embedding
, S extends Point> {
/** Transform a space point into a subspace point.
* @param pt n-dimension point of the space
* @return lower-dimension point of the subspace corresponding to
* the specified space point
* @see #toSpace
*/
S toSubspace(P pt);
/** Transform a collection of space points into subspace points.
* @param pts collection of n-dimension points to transform
* @return collection of transformed lower-dimension points.
* @see #toSubspace(Point)
*/
default List toSubspace(final Collection
pts) {
return pts.stream().map(this::toSubspace).collect(Collectors.toList());
}
/** Transform a subspace point into a space point.
* @param pt 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 pt);
/** Transform a collection of subspace points into space points.
* @param pts collection of lower-dimension points to transform
* @return collection of transformed n-dimension points.
* @see #toSpace(Point)
*/
default List
toSpace(final Collection pts) {
return pts.stream().map(this::toSpace).collect(Collectors.toList());
}
}