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Morse code decoder, please help me

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minyeop jeon
minyeop jeon 2018-6-7
编辑： DGM 2024-8-27
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.
  2 个评论
Walter Roberson
Walter Roberson 2018-6-7
Hint: once you have broken the input up into pieces, you can match by using ismember()
Adam
Adam 2018-6-7
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)

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采纳的回答

Jan
Jan 2018-6-7
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))
  3 个评论
显示 1更早的评论
minyeop jeon
minyeop jeon 2018-6-11
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
Jan 2018-6-11
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.

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更多回答（2 个）

Rishabh Rathore
Rishabh Rathore 2018-6-7
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
  2 个评论
minyeop jeon
minyeop jeon 2018-6-11
Thank you for your informations.
Maddie Long
Maddie Long 2020-2-12
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

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Jair Abdiel
Jair Abdiel 2024-8-27
编辑：Walter Roberson 2024-8-27
%% Codigo Morse Jair Hdz.
% Enlaces Guía
% https://la.mathworks.com/help/matlab/ref/input.html
clear all; clc;
morse={'.-','-...','-.-.','-..','.','..-.','--.','....','..','.---','-.-','.-..','--','-.','---','.--.','--.-','.-.','...','-','..-','...-','.--','-..-','-.--','--..'};
letras={'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'};
text=input ('Texto: \n',"s");
for i=1:length(text)
for j=1:length(letras)
if strcmpi(text(i),letras(j))==1
disp(morse(j))
end
end
end
  1 个评论
DGM
DGM 2024-8-27
Ran in:
This is an encoder, not a decoder. It also just dumps the results to console in an unusable format, one quoted symbol per line, but that's what all the other example do too. Regardless of whether everyone else is doing it that way, it means that the output of your encoder can't actually be used by any decoder.
Consider the example encoder/decoder pair. No loops, rudimentary support for numbers and interword spaces.
% the input
text = 'blah 123';
% the lookup tables
morse = {'.-','-...','-.-.','-..','.','..-.','--.','....','..','.---','-.-','.-..','--','-.', ...
'---','.--.','--.-','.-.','...','-','..-','...-','.--','-..-','-.--','--..', ...
'-----','.----','..---','...--','....-','.....','-....','--...','---..','----.',' '};
letter = ['A':'Z' '0':'9' ' '];
% encode
text = regexprep(upper(text),'[^A-Z0-9 ]',''); % sanitize input
[~, index] = ismember(num2cell(text),num2cell(letter)); % lookup
encoded = strjoin(morse(nonzeros(index)),' ') % assemble output
encoded = '-... .-.. .- .... .---- ..--- ...--'
% decode
symbol = strrep(encoded,' ',' # '); % temporarily replace long spaces
symbol = strsplit(symbol,' '); % split
symbol = strrep(symbol,'#',' '); % recover inter-word spaces
[~, index] = ismember(symbol, morse); % lookup
decoded = letter(nonzeros(index)) % assemble output
decoded = 'BLAH 123'
Both the encoded and decoded outputs are actually stored in usable variables instead of just being displayed and immediately discarded.

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