for loop that changes specific letters to numbers

Asked by Seaturtle on 2 Oct 2019

Latest activity Commented on by Adam Danz on 4 Oct 2019

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I want to replace the vowels AEIOU with the number 0 and all other letters with the number 1. For example the output should be ans = [0 1 1 1 0] if the user inputs apple. I know I must be misunderstanding how to get the loop to go through my whole string. This is what I have managed so far.

party = input('What is your answer? ', 's');
n = length(party)
for i = 1:n
    if i == 'A'
       disp(0)
    elseif i == 'B'
        disp(1)
    elseif i == 'C' 
        disp(1)
    end
end

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3 Answers

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Answer by Walter Roberson on 2 Oct 2019

Accepted Answer

party = input('What is your answer? ', 's');
n = length(party)
for i = 1:n
    if party(i) == 'A'
       party(i) = 0;
    elseif i == 'B'
       party(i) = 1;
    elseif i == 'C' 
       party(i) = 1;
    end
end
disp( double(party) )

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Seaturtle on 3 Oct 2019

I ended up making the changes myself with the original answer that you posted, so it worked out great. Thank you!

Guillaume on 3 Oct 2019

It would be nice if 'vowel' were a category option.

The problem with that is what is a vowel or not depends on the language. Some letters such as 'y' in english can also qualify as a vowel or consonant depending on the word.

Adam Danz on 3 Oct 2019

True. It would be neat to play around with one of the vowel classification algorithms that are not specific to any language such as this one (link below) that is based on character co-occurrences. It wouldn't necessarily solve the fuzzy set problem but it would be a semi-objective, language-independent classification.

https://www.aclweb.org/anthology/W17-4112/

https://www.aclweb.org/anthology/W17-4112.pdf

Link

Answer by Adam Danz on 2 Oct 2019

Edited by Adam Danz on 2 Oct 2019

No loop needed.

str = 'apple'; 
isConsonant = ~ismember(lower(str),'aeiou') %lower() makes it not case sensitive

If you really wanted to do that in a loop,

n = numel(party);
isConsonant = true(1,n); 
for i = 1:n
    if ismember(party(i),'aeiou')
        isConsonant(i) = false; 
    end
end

In both cases, isConsonant is a logical vector. If you want a double vector of 0/1 instead of false/true,

isConsonant = double(isConsonant);

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Walter Roberson on 3 Oct 2019

semi-vowel does sound like the correct term.

In practice, y probably acts like a vowel more than it acts like a consontant .

Seaturtle on 3 Oct 2019

Thanks for this answer! This really helped with my understanding of not using a loop to do something with shorter code.

Adam Danz on 3 Oct 2019

Glad I could chip in! :)

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Answer by Jos (10584) on 3 Oct 2019

Another option:

str = 'apple'; 
TF1 = any(lower(str) ~= 'aeiou'.') 

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Walter Roberson on 3 Oct 2019

TF1 = all(lower(str) ~= 'aeiou'.')

Jos (10584) on 4 Oct 2019

Thanks for the corrections :-)

Adam Danz on 4 Oct 2019

This implicit expansion solution is faster and neater than my ismember() solution.

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