Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.examples.group.bgd.data;
020
021import org.apache.reef.examples.group.utils.math.Vector;
022
023/**
024 * Example implementation on a index and value array.
025 */
026public final class SparseExample implements Example {
027
028  private static final long serialVersionUID = -2127500625316875426L;
029
030  private final float[] values;
031  private final int[] indices;
032  private final double label;
033
034  public SparseExample(final double label, final float[] values, final int[] indices) {
035    this.label = label;
036    this.values = values;
037    this.indices = indices;
038  }
039
040  public int getFeatureLength() {
041    return this.values.length;
042  }
043
044  @Override
045  public double getLabel() {
046    return this.label;
047  }
048
049  @Override
050  public double predict(final Vector w) {
051    double result = 0.0;
052    for (int i = 0; i < this.indices.length; ++i) {
053      result += w.get(this.indices[i]) * this.values[i];
054    }
055    return result;
056  }
057
058  @Override
059  public void addGradient(final Vector gradientVector, final double gradient) {
060    for (int i = 0; i < this.indices.length; ++i) {
061      final int index = this.indices[i];
062      final double contribution = gradient * this.values[i];
063      final double oldValue = gradientVector.get(index);
064      final double newValue = oldValue + contribution;
065      gradientVector.set(index, newValue);
066    }
067  }
068}