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A Java's Collaborative Filtering library to carry out experiments in research of Collaborative Filtering based Recommender Systems. The library has been designed from researchers to researchers.

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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.math3.geometry.partitioning;

import org.apache.commons.math3.geometry.Point;
import org.apache.commons.math3.geometry.Space;

/** Class holding the result of point projection on region boundary.
 * This class is a simple placeholder, it does not provide any
 * processing methods.
 * Instances of this class are guaranteed to be immutable
 * @param  Type of the space.
 * @since 3.3
 * @see AbstractRegion#projectToBoundary(Point)
 */
public class BoundaryProjection {

    /** Original point. */
    private final Point original;

    /** Projected point. */
    private final Point projected;

    /** Offset of the point with respect to the boundary it is projected on. */
    private final double offset;

    /** Constructor from raw elements.
     * @param original original point
     * @param projected projected point
     * @param offset offset of the point with respect to the boundary it is projected on
     */
    public BoundaryProjection(final Point original, final Point projected, final double offset) {
        this.original  = original;
        this.projected = projected;
        this.offset    = offset;
    }

    /** Get the original point.
     * @return original point
     */
    public Point getOriginal() {
        return original;
    }

    /** Projected point.
     * @return projected point, or null if there are no boundary
     */
    public Point getProjected() {
        return projected;
    }

    /** Offset of the point with respect to the boundary it is projected on.
     * 
     * The offset with respect to the boundary is negative if the {@link
     * #getOriginal() original point} is inside the region, and positive otherwise.
     * 
     * 
     * If there are no boundary, the value is set to either {@code
     * Double.POSITIVE_INFINITY} if the region is empty (i.e. all points are
     * outside of the region) or {@code Double.NEGATIVE_INFINITY} if the region
     * covers the whole space (i.e. all points are inside of the region).
     * 
     * @return offset of the point with respect to the boundary it is projected on
     */
    public double getOffset() {
        return offset;
    }

}