- Not that I know of. If it were a logical vector this would indeed be the way to do it, but since linear indices are returned, this might be the only way.
- Longer code can actually be more optimal, and more readable. That being said, as long as you are aware where the bottlenecks of your code are, you are miles ahead of many users. Unless your function is doing this millions of times in a loop, I don't think it is worth the extra effort to optimize this particular issue.
Index to elements not listed in numeric index?
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Andrew Landau
il 25 Nov 2018
Commentato: Andrew Landau
il 25 Nov 2018
Some functions return lists of indices, such as unique and ismember. Let's say I want to index to every element that isn't listed:
A = [1 1 2 2 3 3];
[uA, idxuA] = unique(A); % uA = [1 2 3], idxuA = [1 3 5]
idxDuplicates = true(length(A),1);
idxDuplicates(idxuA) = false;
duplicatesInA = A(idxDuplicates);
But it seems like that isn't very efficient and it would be nice to do something like-
duplicatesInA = A(~idxuA);
I really have two questions for the matlab/coding experts:
(1) Is there an efficient and direct way to use the '~' for a list of indices
(2) Is it worth it to optimize this or should I just deal with the extra few lines of code?
2 Commenti
Rik
il 25 Nov 2018
I don't really consider myself to be an expert, but I'll still add my thoughts on this:
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Matt J
il 25 Nov 2018
Modificato: Matt J
il 25 Nov 2018
Is it worth it to optimize this or should I just deal with the extra few lines of code?
There's never a reason to deal with extra lines of code if it's an operation that you do often. That's what mfunctions are for.
function Ac = complement(A,idx)
Ic=true(numel(A),1);
Ic(idx)=false;
Ac=A(lc(idx));
end
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