java - Entropielist for Morsecode

Question

Hey guys I have got a question...we have to do an assignment where we have to translate normal text code into morse code in Processing (Java). We also have to calculate entropy and redundancy. The translation is working, but we can't figure out how we can calculate the probability for all the chars at ones to calculate the entropy.

    import controlP5.*;
import java.util.Map;
// dot = one unit
// dash = three units
// space between parts of the same letter = one unit
// space between letter = three units
// space between words is seven units

float x= 50;
float y= 450;
float w= 500;
float h = 80;

ControlP5 cp5;

String input;
String convert_string;
String output;
String temp;
Textarea myTextarea;
Textarea addTextarea;

String[] alphabet = {
  "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", 
  "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", " "
};
String[] morse = {
  "._", "_...", "_._.", "_..", ".", ".._.", "__.", "....", "..", ".___", "_._", "._..", "__", 
  "_.", "___", ".__.", "__._", "._.", "...", "_", ".._", "..._", ".__", "_.._", "_.__", "__..", "/"
};

int countLetter(String str, char zeichen) {
  str = str.toLowerCase();
  int count = 0;

  for (int i = 0; i < str.length(); i++) {
    char currentLetter = str.charAt(i);
    if (currentLetter == zeichen)
      count++;
  }

  return count;
}

double getAverageCharLength(String str) {
  String words[] = str.split("/");
  int numWords = words.length;
  int totalCharacters = 0;
  for (int i = 0; i < numWords; i++) {
    totalCharacters = totalCharacters + words[i].length();
  }
  return totalCharacters/numWords;
}


void setup() {
  size(600, 600);
  convert_string= "";
  temp = "";
  input = "";
  output = "";
  cp5 = new ControlP5(this);

  cp5.addTextfield("Input").setPosition(50, 100).setSize(100, 50).setAutoClear(false);
  cp5.addBang("Submit").setPosition(50, 200).setSize(100, 50);
  myTextarea = cp5.addTextarea("Output")
    .setPosition(200, 100)
    .setSize(300, 300)
    .setFont(createFont("arial", 20))
    .setLineHeight(25)
    .setColor(color(255))
    .setColorBackground(color(255, 100))
    .setColorForeground(color(255, 100));
  ;
  addTextarea = cp5.addTextarea("AddOutput")
    .setPosition(200, 450)
    .setSize(300,100)
    .setFont(createFont("arial", 14))
    .setLineHeight(14)
    .setColor(color(255))
    .setColorBackground(color(255, 100))
    .setColorForeground(color(255, 100));
  ;
  
}



void draw() {
  background(0);
  
}

public void Submit() {
  input = cp5.get(Textfield.class, "Input").getText();
  convert_string = input.toLowerCase();
  float otput = output.length();
  float oput =0;

  for (int i=0; i<convert_string.length(); i++) {
    for (int j=0; j<alphabet.length; j++) {
      if (String.valueOf(convert_string.charAt(i)).equals(alphabet[j])) {
        output += morse[j]+' ';
        otput= otput-1;
      }
    }
  }
 
double entropie = 0;
  double wortlaenge = 0;
  double charProbability=0;
  float curCharCount= 0;
  float inputLength = input.length();
  float entcounter=0;

  // Anzahl der einzelnen Zeichen im Eingabestring
  HashMap<Character,Integer> map = new HashMap<Character,Integer>();
  for(int i = 0; i < input.length(); i++){
    char c = input.toLowerCase().charAt(i);
    Integer val = map.get(c);
    if(val != null){
      map.put(c, new Integer(val + 1));
    }else{
      map.put(c,1);
    }
  

  // iteriert über Zeichen der Eingabe und berechnet Entropie und Wortl?nge
  for (HashMap.Entry<Character, Integer> me : map.entrySet()) {
    curCharCount = me.getValue();
    charProbability = curCharCount / input.length();

    // Wortl?nge für aktuelles Zeichen aus Morsekode-Map holen
 // if (convert_string.get(me.getKey())) != null) {
   //   wortlaenge += charProbability * get(me.getKey()).length();
    }
  }
  //entropie=entropie/entcounter;
  oput= output.length()+otput; 
  wortlaenge += charProbability * oput;
  
      entropie = charProbability * (Math.log(charProbability) / Math.log(2));
      
  println(wortlaenge);
  println(charProbability);
  println(entropie);
  println(inputLength);
  }
  //entropie = -entropie;
//  double redundanz = wortlaenge - entropie; 
  
  
  
  
/*  println(output);
  temp= output;
  myTextarea.setText(output);
  output = "";
  addTextarea.setText("Durchschnittliche Wortl?nge : "+ getAverageCharLength(temp) +"
");
   println(countLetter(temp, '_'));
   println(countLetter(temp, '.'));
   println(countLetter(temp, '/'));
   */
//}

question from:https://stackoverflow.com/questions/65940680/entropielist-for-morsecode

Answer 1

How should the entropy and redundancy be calculated? Do you have a formula or a link to a definition? That would make your requirements clearer.

What do you mean by "calculate the probability for all the chars at ones to calculate the entropy"?

There are two questions on Stack Overflow that are also related to Morse code and Processing, so these might be helpful (although they seem to be mainly about decoding Morse code):

• Morse Code Decoder on Processing Adaptation Problem
• Converting Morse Code encoder to decoder in Processing 3 Problem