001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.math3.fitting;
018
019import java.util.List;
020import java.util.ArrayList;
021import java.io.Serializable;
022
023/**
024 * Simple container for weighted observed points used
025 * in {@link AbstractCurveFitter curve fitting} algorithms.
026 *
027 * @since 3.3
028 */
029public class WeightedObservedPoints implements Serializable {
030    /** Serializable version id. */
031    private static final long serialVersionUID = 20130813L;
032
033    /** Observed points. */
034    private final List<WeightedObservedPoint> observations
035        = new ArrayList<WeightedObservedPoint>();
036
037    /**
038     * Adds a point to the sample.
039     * Calling this method is equivalent to calling
040     * {@code add(1.0, x, y)}.
041     *
042     * @param x Abscissa of the point.
043     * @param y Observed value  at {@code x}. After fitting we should
044     * have {@code f(x)} as close as possible to this value.
045     *
046     * @see #add(double, double, double)
047     * @see #add(WeightedObservedPoint)
048     * @see #toList()
049     */
050    public void add(double x, double y) {
051        add(1d, x, y);
052    }
053
054    /**
055     * Adds a point to the sample.
056     *
057     * @param weight Weight of the observed point.
058     * @param x Abscissa of the point.
059     * @param y Observed value  at {@code x}. After fitting we should
060     * have {@code f(x)} as close as possible to this value.
061     *
062     * @see #add(double, double)
063     * @see #add(WeightedObservedPoint)
064     * @see #toList()
065     */
066    public void add(double weight, double x, double y) {
067        observations.add(new WeightedObservedPoint(weight, x, y));
068    }
069
070    /**
071     * Adds a point to the sample.
072     *
073     * @param observed Observed point to add.
074     *
075     * @see #add(double, double)
076     * @see #add(double, double, double)
077     * @see #toList()
078     */
079    public void add(WeightedObservedPoint observed) {
080        observations.add(observed);
081    }
082
083    /**
084     * Gets a <em>snapshot</em> of the observed points.
085     * The list of stored points is copied in order to ensure that
086     * modification of the returned instance does not affect this
087     * container.
088     * Conversely, further modification of this container (through
089     * the {@code add} or {@code clear} methods) will not affect the
090     * returned list.
091     *
092     * @return the observed points, in the order they were added to this
093     * container.
094     *
095     * @see #add(double, double)
096     * @see #add(double, double, double)
097     * @see #add(WeightedObservedPoint)
098     */
099    public List<WeightedObservedPoint> toList() {
100        // The copy is necessary to ensure thread-safety because of the
101        // "clear" method (which otherwise would be able to empty the
102        // list of points while it is being used by another thread).
103        return new ArrayList<WeightedObservedPoint>(observations);
104    }
105
106    /**
107     * Removes all observations from this container.
108     */
109    public void clear() {
110        observations.clear();
111    }
112}