MATLAB: How to select values of array using the logical operator “OR”

arrayMATLABmatrix manipulationsymbolic

GOAL: Hi, I have an array A and want to build a new array B by selecting two or more values using the logical operator OR.
MY SOLUTION: I wrote the following lines:
A=[1 3 4 3 7 8 5 4 6 5]';
B= zeros(size(A));
for i = 1:numel(A) 
    if A(i) == 3 || 5;
       B(i) = A(i);       
    else
       B(i) = NaN;
    end
end
PROBLEM: The logical operator OR is not working. The array B is not correct because it is identical to array A. As a result I expected to see:
NaN
3
NaN
3
NaN
NaN
5
NaN
NaN
5
However, If I remove the logical operator OR, B is correct but does not include the value 5.
I wonder if someone could tell me what I'm doing wrong and how to correct these lines.
Thank you in advance for your attention
Emerson

Best Answer

Try
if A(i) == 3 || A(i) == 5  % BTW, no trailing semicolon needed.
Or, better yet, try this vectorized way:
A = [1 3 4 3 7 8 5 4 6 5]'
indexesToReplace = A == 3 | A == 5
B = nan(size(A));
B(indexesToReplace) = A(indexesToReplace)
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