i am not getting what is the problem with it

Question

RITISH 2022-12-16

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编辑： Torsten 2022-12-16

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Given three input variables:

hotels - a list of hotel names
ratings - their ratings in a city
cutoff - the rating at which you would like to cut off

return only the names of those hotels with a rating of cutoff value or above as a column vector of strings good.

So this is one of the question from cody.I tried it like this-

function good = find_good_hotels(hotels,ratings,cutoff)
if ratings>=cutoff
    Ridx=find(ratings)
    good=hotels(Ridx)
end

but it said the code ran without an output.

but when i ran with this folloowing code it worked.

function good = find_good_hotels(hotels,ratings,cutoff)
    Ridx=find(ratings>=cutoff)
    good=hotels(Ridx)
end

Isnt both code similar? The former one with "if" should run also right.Or please clear me out where i am getting wrong.

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Answer 1

Voss 2022-12-16

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function good = find_good_hotels(hotels,ratings,cutoff)
if ratings>=cutoff
    Ridx=find(ratings)
    good=hotels(Ridx)
else
    % if ratings < cutoff, then "good" is undefined, so no output is produced
end

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RITISH 2022-12-16

So what can be used in this case to get the output with the "if" statement

Voss 2022-12-16

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If you want to use the "if" statement approach, you'll also need a for loop, since ratings is a vector.

It's better to use a logical indexing approach:

function good = find_good_hotels(hotels,ratings,cutoff)
    good=hotels(ratings>=cutoff);
end

which is even simpler than the find approach.

But here's the "if" approach:

function good = find_good_hotels(hotels,ratings,cutoff)
    good = strings(0,1);
    for ii = 1:numel(hotels)
        if ratings(ii) >= cutoff
            good(end+1,1) = hotels(ii);
        end
    end
end

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Answer 2

Torsten 2022-12-16

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https://ww2.mathworks.cn/matlabcentral/answers/1879872-i-am-not-getting-what-is-the-problem-with-it#answer_1129717

编辑：Torsten 2022-12-16

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function good = find_good_hotels(hotels,ratings,cutoff)
  if ratings>=cutoff
    Ridx=find(ratings)
    good=hotels(Ridx)
  end
end

The if-statement does not make sense. The inner of the if-statement is executed only if for all components i of the array ratings, the condition ratings(i)>=cutoff is satisfied. In this case, the indices of the nonzero elements of "ratings" are written in Ridx which also makes no sense because they have to be compared to the value "cutoff".

The easiest solution is simply

good = hotels(ratings>=cutoff)