array dimensions equivalence check?

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Walter Roberson
Walter Roberson 2012-1-4
编辑： Bruno Luong 2022-4-23
You would think I would know this by now, but I never had reason to program it before.
Is there a good idiom for efficiently checking that two arrays are the same size or are row and column vectors of the same length?
For example, this kind of check would be used to find out whether two arrays are assignment-compatible, or to find out if two arrays are compatible for plot() purposes.
The code I have come up with feels overly complicated:
szA = size(A);
szB = size(B);
if isequal(szA,szB) || ...
(sum(szA==1) == 1 && sum(szB==1) == 1 && ...
numel(szA)==2 && numel(szB)==2) && ...
prod(szA) == prod(szB))
Which is to say, the sizes can be identical, or they can both be 2 dimensional with exactly one of the dimensions of each being 1, and the number of elements the same between the two.
This kind of check must be programmed all over the place. Perhaps there is a utility routine that I overlooked?
  2 个评论
Bruno Luong
Bruno Luong 2022-4-23
编辑：Bruno Luong 2022-4-23
Ran in:
Your test return false for
A = [];
B = zeros(1,0);
however plot works just fine
plot(A,B)
or Assignment
X = rand();
X(1,[])=X([],[]) % B on lhs, A on rhs
X = 0.6365

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采纳的回答

David Young
David Young 2012-1-4
One alternative:
isequal(size(A), size(B)) || (isvector(A) && isvector(B) && numel(A) == numel(B))
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显示 1更早的评论
Adam Wyatt
Adam Wyatt 2021-11-18
This will return true if A is a row vector and B is a column vector (or vice versa). If you care about that:
isequal(size(A), size(B)) || ( ...
((iscolumn(A) && iscolumn(B)) || (isrow(A) && isrow(B))) ...
&& isequal(numel(A), numel(B)))
Ahmed
Ahmed 2022-4-23
This seems not working for 3-D arrays or higher. Therefore, I implemented a more general function below.

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