霍夫曼編碼 - 分組符號

Question

我使用互聯網上發現的霍夫曼編碼來獲取作爲矩陣存儲在二維數組中的隨機整數的頻率。

鏈接霍夫曼碼 - Java的：http://rosettacode.org/wiki/Huffman_coding

方法Q1要求用戶設置的矩陣大小。該矩陣填充隨機整數[0,255]。

public void q1(){ 
    System.out.println(); 
    System.out.println("Question 1 - Creating Random Matrix"); 

    Scanner in = new Scanner(System.in); 

    //Matrix number of rows 
    System.out.print("Insert size of rows M: "); 
    rows = in.nextInt(); 

    //Matrix number of columns 
    System.out.print("Insert size of columns N: "); 
    columns = in.nextInt(); 

    System.out.println(); 

    matrix = new int[rows][columns]; 

    //Initialising randomisation 
    Random r = new Random(); 

    //Filling matrix and printing values 
    for (int m = 0; m < rows; m++){ 
     for (int n = 0; n < columns; n++){ 
      matrix[m][n] = r.nextInt(256); 
      System.out.print("[" + matrix[m][n] + "] \t"); 
     } 
     System.out.print("\n"); 
    } 
    System.out.println(); 
} 

方法Q2需要重新顯示在矩陣中找到的所有隨機整數及其頻率。

public void q2() { 
    // we will assume that all our characters will have code less than 256, for simplicity 
    int[] charFreqs = new int[256]; 
    StringBuilder sb = new StringBuilder(); 
    String [] st = new String[5]; 

    System.out.println(); 
    System.out.println("Alphabet " + "\t" + "Frequency" + "\t" + "Probability"); 
    for (int m = 0; m < rows; m++){ 
     for (int n = 0; n < columns; n++){ 
      String sentence = String.valueOf(matrix[m][n]); 
      System.out.print(matrix[m][n] + "\n"); 

      //read each character and record the frequencies 
      for (int i = 0; i < sentence.length(); i++){ 
       char c = sb.append(sentence[i]); 
      } 

      for (char c : sentence.toCharArray()){ 
       charFreqs[c]++; 
      } 
     } 
    }  

    // build tree 
    HuffmanTree tree = buildTree(charFreqs); 

    // print out results 
    System.out.println("SYMBOL\tWEIGHT\tHUFFMAN CODE"); 
    printCodes(tree, new StringBuffer()); 
} 

當前程序通過將隨機整數分成單獨的數字來計算頻率。我需要計算每個隨機整數的頻率。

請幫忙嗎？

謝謝

Answer 1

一個相當簡單的方式，你可以使用Java 8流（如果他們提供給你）這樣做：

Map<Integer, Integer> frequencies = Arrays.stream(matrix) 
    .flatMap(Arrays::stream) 
    .collect(Collectors.groupingBy(Function.identity(), Collectors.counting());