content: /*
   * (C) Copyright 2014 Amaury Crickx
   *
   * Licensed 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 com.bitsinharmony.recognito.distances;
  
  /**
   * Abstract base class for distance calculators
   * 
   * @author Amaury Crickx
   */
  public abstract class DistanceCalculator {
  
      public abstract double getDistance(double[] features1, double[] features2);
      
      /**
       * Nullity check of parameters
       * @param features1 the first features vector
       * @param features2 the secund features vector
       * @return Double.POSITIVE_INFINITY in case either or both of the vectors are null, a negative number otherwise
       */
      protected double positiveInfinityIfEitherOrBothAreNull(double[] features1, double[] features2) {
          if(features1 == null || features2 == null) {
              return Double.POSITIVE_INFINITY;
          } else {
              return -1.0d;
          }
      }
  }
  