/*
    * 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
    *
    *      https://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.
   */
  
  /*
   * This is not the original file distributed by the Apache Software Foundation
   * It has been modified by the Hipparchus project
   */
  package org.hipparchus.stat.descriptive.vector;
  
  import java.io.Serializable;
  import java.util.Arrays;
  
  import org.hipparchus.exception.LocalizedCoreFormats;
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.stat.descriptive.StorelessMultivariateStatistic;
  import org.hipparchus.stat.descriptive.StorelessUnivariateStatistic;
  import org.hipparchus.util.MathUtils;
  
  /**
   * Uses an independent {@link StorelessUnivariateStatistic} instance
   * for each component of a vector.
   */
  public class VectorialStorelessStatistic
      implements StorelessMultivariateStatistic, Serializable {
  
      /** Serializable UID */
      private static final long serialVersionUID = 20160413L;
  
      /** Statistic for each component */
      private final StorelessUnivariateStatistic[] stats;
  
      /**
       * Create a new VectorialStorelessStatistic with the given dimension
       * and statistic implementation. A copy of the provided statistic
       * will be created for each component of the vector.
       *
       * @param dimension the vector dimension
       * @param univariateStatistic the prototype statistic
       * @throws MathIllegalArgumentException if dimension < 1
       */
      public VectorialStorelessStatistic(int dimension,
                                         StorelessUnivariateStatistic univariateStatistic) {
          if (dimension < 1) {
              throw new MathIllegalArgumentException(LocalizedCoreFormats.NUMBER_TOO_SMALL,
                                                     dimension, 1);
          }
          stats = new StorelessUnivariateStatistic[dimension];
          for (int i = 0; i < dimension; i++) {
              stats[i] = univariateStatistic.copy();
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public void increment(double[] d) {
          MathUtils.checkDimension(d.length, stats.length);
          for (int i = 0; i < stats.length; i++) {
              stats[i].increment(d[i]);
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public double[] getResult() {
          double[] result = new double[stats.length];
          for (int i = 0; i < result.length; ++i) {
              result[i] = stats[i].getResult();
          }
          return result;
      }
  
      /** {@inheritDoc} */
      @Override
      public long getN() {
          return stats[0].getN();
      }
  
      /** {@inheritDoc} */
      @Override
      public void clear() {
          for (StorelessUnivariateStatistic stat : stats) {
              stat.clear();
          }
      }
  
     /** {@inheritDoc} */
     @Override
     public int getDimension() {
         return stats.length;
     }
 
     /** {@inheritDoc} */
     @Override
     public int hashCode() {
         final int prime = 31;
         int result = 1;
         result = prime * result + Arrays.hashCode(stats);
         return result;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
         }
         if (!(obj instanceof VectorialStorelessStatistic)) {
             return false;
         }
         VectorialStorelessStatistic other = (VectorialStorelessStatistic) obj;
         if (!Arrays.equals(stats, other.stats)) {
             return false;
         }
         return true;
     }
 
 }