[matlab] Morse code decoder, please help me

text1=string(input ('(Please Enter morse code: \n','s'));

morse={'.-','-...','-.-.','-..','.','..-.','--.','....','..','.---','-.-','.-..','--','-.','---','.--.','--.-','.-.','...','-','..-','...-','.--','-..-','-.--','--..'};

letter={'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'};

for i=1:length(text1)

      for j=1:length(letter)
        if strcmpi(text1(i),morse(j))==1
          disp(letter(j));     
        end
      end
  end

--------------------------------------------------------------------

This is my code.

When I enter '.-' on matlab commander it display 'A'. But if I enter '.- -...' to show 'A' 'B', Matlab can not read it.

Help.

[Walter Roberson]

Hint: once you have broken the input up into pieces, you can match by using ismember()

[Adam]

It would probably be more efficient to use

doc containers.Map

to put your morse letters as keys and ordinary letters as values (and vice versa if you want the reverse too)

Answer 1

[Jan]

Or:

text1 = input('Please Enter morse code: \n', 's');

morse = {'.-','-...','-.-.','-..','.','..-.','--.','....','..','.---','-.-','.-..', ...
         '--','-.','---','.--.','--.-','.-.','...','-','..-','...-','.--','-..-', ...
         '-.--','--..'};
letter = char('A':'Z');

symbol = strsplit(text1, ' ');
for i = 1:length(symbol)
  disp(letter(ismember(morse, symbol{i}))
end

Or without a loop:

[~, index] = ismember(symbol, morse);
disp(letter(index))

[Stephen23]

+1 very tidy use of ismember.

[minyeop jeon]

Thank you so much. I want to know the meaning of ' [~, index] = ismember(symbol, morse);'. I'm not good at English so I can't find about the function of [~, name]. Could you inform links or explations of it to me?

[Jan]

The tilde ~ means, that this output argument is not used. It is equivalent to:

[dummy, index] = ismember(symbol, morse);

and then ignoring the value of the variable dummy. All you need for the decoding is the 2nd output of ismember.

Answer 2

[Rishabh Rathore]

The problem with your solution is, you are comparing '.- -...' to '.-'.

First break the input string to individual morse letters and then run the loop.

Make the following changes in your code, it should work fine

text1=string(input ('(Please Enter morse code: \n','s'));

morse={'.-','-...','-.-.','-..','.','..-.','--.','....','..','.---','-.-','.-..','--','-.','---','.--.','--.-','.-.','...','-','..-','...-','.--','-..-','-.--','--..'};

letter={'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'};
%-----Changes----
text1=textscan(text1,'%s','Delimiter',' '); %getting individual morse letters

text1=text1{1};
%----------------
for i=1:length(text1)
    for j=1:length(letter)
      if strcmpi(text1(i),morse(j))==1
        disp(letter(j));     
      end
    end
end

[minyeop jeon]

Thank you for your informations.

[Maddie Long]

Hi, what if we want to send in mutiple letters? for example

test1 = .... ..

i get the error

"index exceeds the number of array elements"

thanks