优化版 JAVA 最大熵模型（GIS 训练）

网上现有的最大熵模型，如：https://blog.csdn.net/nwpuwyk/article/details/37500371
该代码在训练环节性能较差，特征函数存储的结构也涉及较简单。
我在该版本基础上进行了改进，优化了特征函数的数据结构和训练代码。

     /**
   * 样本数据集
   */
  List<Instance> instanceList = new ArrayList<Instance>();
  /**
   * 特征列表，来自所有事件的统计结果
   */
​

// Map<String,Feature> featureMap=new HashMap<>();
/**
* 每个特征的出现次数
*/
//Map<String,Integer> featureCountMap=new HashMap<>();
/**
* 事件（类别）集
*/
List labels = new ArrayList();
/**
* 每个特征函数的权重
*/
// double[] weight;
Map<String,Weight> weightMap=new HashMap<>();
/**
* 一个事件最多一共有多少种特征
*/
double learningRate=10;
int C;
Map<String,List> testInstance;
/**
* 样本数据集 */ List instanceList = new ArrayList();
/**
* 特征列表，来自所有事件的统计结果 */// Map featureMap=new HashMap<>();
/**
* 每个特征的出现次数 */ //Map featureCountMap=new HashMap<>();
/**
* 事件（类别）集 */ List labels = new ArrayList();
/**
* 每个特征函数的权重 */ // double[] weight;
Map<String,Weight> weightMap=new HashMap<>();
/**
* 一个事件最多一共有多少种特征 */ double learningRate=10;
int C;

   * 训练模型 * @param maxIt 最大迭代次数
   */public void train(int maxIt,String savePath) throws IOException {
      Map,Double> empiricalE = new HashMap<>(); // 经验期望
    Map,Double> modelE = new HashMap<>(); // 模型期望

    for (Map.Entry,Weight> e:weightMap.entrySet())
      {
          double ratio=(double) e.getValue().getCnt() / instanceList.size();
    empiricalE.put(e.getKey(),ratio);
    }
      Map,Double> lastWeight=new HashMap<>();
   for (int i = 0; i < maxIt; ++i)
      {
          System.out.println("iter:"+i);
    computeModeE(modelE);//计算模型期望
    System.out.println("model finish.updating...");
   for (Map.Entry,Weight> e:weightMap.entrySet())
          {
             //lastWeight[w] = weight[w];
    lastWeight.put(e.getKey(),e.getValue().getWeight());
    String f=e.getKey();
   double delta=learningRate / C * Math.log(empiricalE.get(f)/ modelE.get(f));
    weightMap.get(f).addWeight(delta);
    }
          System.out.println("saving iter:"+i);
    learningRate*=0.99;
    learningRate=learningRate<10?10:learningRate;
    saveParam(savePath+"ent_insopt.par"+i);
   if (checkConvergence(lastWeight, weightMap)) break;

    }

  }

  /**
   * 预测类别 * @param fieldList
    * @return
    */
  public Pair, Double>[] predict(Map,Integer> fieldList)
  {
      double[] prob = calProb(fieldList);
    Pair, Double>[] pairResult = new Pair[prob.length];
   for (int i = 0; i < prob.length; ++i)
      {
          pairResult[i] = new Pair, Double>(labels.get(i), prob[i]);
    }

      return pairResult;
  }

  /**
   * 检查是否收敛 * @param w1
    * @param w2
    * @return 是否收敛
   */public boolean checkConvergence(Map,Double> w1, Map,Weight> w2)
  {
      System.out.println("w1 size:"+w1.size());
   boolean flag=true;
   for (Map.Entry,Double> e1:w1.entrySet())
      {
          //System.out.println("thread:"+Math.abs(e1.getValue() - w2.get(e1.getKey())) );
    if (Math.abs(e1.getValue() - w2.get(e1.getKey()).getWeight()) >= 1e-4)    // 收敛阀值0.01可自行调整
    flag=false;
    }
      return flag;
  }

  /**
   * 计算模型期望，即在当前的特征函数的权重下，计算特征函数的模型期望值。 * @param modelE 储存空间，应当事先分配好内存（之所以不return一个modelE是为了避免重复分配内存）
   */public void computeModeE(Map,Double> modelE)
  {
      modelE.clear();
   double rate=1.0 / instanceList.size();
   for (int i = 0; i < instanceList.size(); ++i)
      {

          Map,Integer> fieldMap = instanceList.get(i).fieldList;//no labels
   //计算当前样本X对应所有类别的概率  double[] pro = calProb(fieldMap);
   for (Map.Entry,Integer> e:fieldMap.entrySet())
          {
              String insFeature=e.getKey();/**
     * 训练模型
     * @param maxIt 最大迭代次数
     */
    public void train(int maxIt,String savePath) throws IOException {
        Map<String,Double> empiricalE = new HashMap<>();   // 经验期望
        Map<String,Double> modelE = new HashMap<>();       // 模型期望

        for (Map.Entry<String,Weight> e:weightMap.entrySet())
        {
            double ratio=(double) e.getValue().getCnt() / instanceList.size();
            empiricalE.put(e.getKey(),ratio);
        }
        Map<String,Double> lastWeight=new HashMap<>();
        for (int i = 0; i < maxIt; ++i)
        {
            System.out.println("iter:"+i);
            computeModeE(modelE);//计算模型期望
            System.out.println("model finish.updating...");
            for (Map.Entry<String,Weight> e:weightMap.entrySet())
            {
               //lastWeight[w] = weight[w];
                lastWeight.put(e.getKey(),e.getValue().getWeight());
                String f=e.getKey();
                double delta=learningRate / C * Math.log(empiricalE.get(f)/ modelE.get(f));
                weightMap.get(f).addWeight(delta);
            }
            System.out.println("saving iter:"+i);
            learningRate*=0.99;
            learningRate=learningRate<10?10:learningRate;
            saveParam(savePath+"ent_insopt.par"+i);
            if (checkConvergence(lastWeight, weightMap)) break;

        }

    }

    /**
     * 预测类别
     * @param fieldList
     * @return
     */
    public Pair<String, Double>[] predict(Map<String,Integer> fieldList)
    {
        double[] prob = calProb(fieldList);
        Pair<String, Double>[] pairResult = new Pair[prob.length];
        for (int i = 0; i < prob.length; ++i)
        {
            pairResult[i] = new Pair<String, Double>(labels.get(i), prob[i]);
        }

        return pairResult;
    }

    /**
     * 检查是否收敛
     * @param w1
     * @param w2
     * @return 是否收敛
     */
    public boolean checkConvergence(Map<String,Double> w1, Map<String,Weight> w2)
    {
        System.out.println("w1 size:"+w1.size());
        boolean flag=true;
        for (Map.Entry<String,Double> e1:w1.entrySet())
        {
            //System.out.println("thread:"+Math.abs(e1.getValue() - w2.get(e1.getKey())) );
            if (Math.abs(e1.getValue() - w2.get(e1.getKey()).getWeight()) >= 1e-4)    // 收敛阀值0.01可自行调整
                flag=false;
        }
        return flag;
    }

    /**
     * 计算模型期望，即在当前的特征函数的权重下，计算特征函数的模型期望值。
     * @param modelE 储存空间，应当事先分配好内存（之所以不return一个modelE是为了避免重复分配内存）
     */
    public void computeModeE(Map<String,Double> modelE)
    {
        modelE.clear();
        double rate=1.0 / instanceList.size();
        for (int i = 0; i < instanceList.size(); ++i)
        {

            Map<String,Integer> fieldMap = instanceList.get(i).fieldList;//no labels
             //计算当前样本X对应所有类别的概率
            double[] pro = calProb(fieldMap);
            for (Map.Entry<String,Integer> e:fieldMap.entrySet())
            {
                String insFeature=e.getKey();
                int cnt=e.getValue();
                for (int k = 0; k < labels.size(); k++)
                {
                    String feature=labels.get(k)+":"+insFeature;
                      if (weightMap.containsKey(feature)) {
                        double  delta=pro[k] * rate*cnt;
                        modelE.put(feature, modelE.containsKey(feature) ? modelE.get(feature) + delta : delta);
                    }
                }
            }
        }
    }
//    public class Mode implements Runnable
//    {
//        ConcurrentLinkedQueue<Integer> insQueue=new ConcurrentLinkedQueue<>();
//        boolean flag=true;
//        List<Instance> i∂
//        public void addIns(int i)
//        {
//
//        }
//
//        @Override
//        public void run() {
//            while(flag)
//            {
//                int ins=insQueue.poll();
//            }
//        }
//    }
    /**
     * 计算p(y|x),此时的x指的是instance里的field
     * @param fieldList 实例的特征列表
     * @return 该实例属于每个类别的概率
     */
    public double[] calProb(Map<String,Integer> fieldList)
    {
        double[] p = new double[labels.size()];
        double sum = 0;  // 正则化因子，保证概率和为1
        for (int i = 0; i < labels.size(); ++i)
        {
            double weightSum = 0;
            String label=labels.get(i);
            for (String field : fieldList.keySet())
            {
                String feature=label+":"+field;
                 if (weightMap.containsKey(feature)) {
                    weightSum += weightMap.get(feature).getWeight()*fieldList.get(field);
                }
            }
            if(weightSum>15)
            {
                weightSum=15;
            }
            p[i] = Math.exp(weightSum);

            sum += p[i];
        }
        //System.out.println();
        for (int i = 0; i < p.length; ++i)
        {
            p[i] /= sum;
//            if(Double.isNaN(p[i]))
//            {
//                System.out.println(p[i]);
//            }
        }
        return p;
    }

    /**
     * 一个观测实例，包含事件和时间发生的环境
     */
    class Instance implements Serializable
    {
        /**
         * 事件（类别），如Outdoor
         */
        String label;
        /**
         * 事件发生的环境集合，如[Sunny, Happy]
         */
        Map<String,Integer> fieldList = new HashMap<>();

        public Instance(String label, Map<String,Integer>fieldList)
        {
            this.label = label;
            this.fieldList = fieldList;
        }
    }

    /**
     * 特征(二值函数)
     */
    class Weight
    {
        double weight=0;
        int cnt=0;
        public void addWeight(double w)
        {
            weight+=(w);
        }
        public double getWeight() {
            return weight;
        }
        public void addCnt(int c)
        {
            cnt+=c;
        }
        public void setWeight(double weight) {
            this.weight = weight;
        }

        public int getCnt() {
            return cnt;
        }

        public void setCnt(int cnt) {
            this.cnt = cnt;
        }
    }
   int cnt=e.getValue();
   for (int k = 0; k < labels.size(); k++)
              {
                  String feature=labels.get(k)+":"+insFeature;
   if (weightMap.containsKey(feature)) {
                      double delta=pro[k] * rate*cnt;
    modelE.put(feature, modelE.containsKey(feature) ? modelE.get(feature) + delta : delta);
    }
              }
          }
      }
  }
​