fails for a similar reason in my eyes. A solution that solves a problem only for specific cases is a bad one, since one day, that code will fail and be difficult to debug. Perhaps someone might argue that

sum(v | ~v)

might have been a better choice. That succeeds as long as none of the elements of v are NaN.

Anyway, a poll like this should help teach newer users what good, robust code looks like, insted of convincing at least one new user out there that sum(v>0) might be an adequate replacement for numel(z).

1 Antwort

goc3 am 14 Mai 2024

Thank you for your comment, John—your insights and experience are appreciated. Aside from the fact that this question refers to a specific vector that contains only positive integers, you do raise some helpful points. I would also mention that poll questions and options/answers have rather small character limits.

That being said, I agree that a novice could misinterpret some of the options as being viable replacements. I would argue that some of them are viable in specific contexts and/or for specific purposes. However, the main point of these polls is to catch a user's attention and make them think—perhaps even causing them to open up the documentation or test out the options. There are many built-in functions that overlap and can be interchanged for specific use cases.

bhagath am 3 Mai 2024

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Josh am 22 Apr. 2024

thank you for continuing with these!

Deepu am 22 Apr. 2024

numel(v): Returns the number of elements in the array v. In this case, it correctly returns 5.
length(v): Returns the number of elements along the longest dimension of the array v. Since v is a vector, length(v) correctly returns 5.
width(v): There is no built-in function named width in MATLAB. Therefore, this option is incorrect.
nnz(v): Returns the number of non-zero elements in the array v. Since all elements in v are non-zero, nnz(v) correctly returns 5.
size(v, 1): Returns the size of the array v along the specified dimension. Since v is a row vector, size(v, 1) correctly returns 1.
sum(v > 0): Returns the sum of elements in the logical array resulting from the condition v > 0. Since all elements in v are greater than 0, sum(v > 0) correctly returns 5.