setdiff error in some cases

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Neesha 2014-9-26

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https://ww2.mathworks.cn/matlabcentral/answers/156310-setdiff-error-in-some-cases

编辑： Neesha 2014-10-2

Hi I am using setdiff in my code and i am getting 'Improper assignment with rectangular empty matrix' error in a particular case , why and how to solve this? my code is as below:

 A = dataset();
 A.Location = {'south'};
 A.Number = 3;
 B= dataset();
 B.Location = {'north'};
 B.Number = 3;
 diff1 = setdiff(A, B); %THIS EXECUTES JUST FINE
 C= dataset();
 C.Location = {'north'};
 C.Number = 3;
 C(1, :) = [];
 D= dataset();
 D.Location = {'west'};
 D.Number = 5;
 D.Location(2, 1) = {'north'};
 diff2 = setdiff(C, D); %THIS EXECUTES JUST FINE
 diff3 = setdiff(C, B); %THIS GIVES ME ERROR MENTIONED ABOVE, WHY?

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Neesha 2014-10-1

Stephen Cobeldick : Yes I have, and that is how i came up with example here with the code.

per isakson : just trying to delete a row, to end up with one row in the dataset

dpb : I am not sure what you meant by 'element' but i think you are describing the problem correctly that setdiff fails when one is empty and not-empty has one row. it does work though with empty dataset if non-empty ha more than one row. What is TMW?

dpb 2014-10-1

...What is TMW?...

The Mathworks, vendors of Matlab. Shorthand for the suggestion you contact official support at www.mathworks.com with a support request for an official interpretation of the behavior observed if you think it's important that the null input case not fail.

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采纳的回答

Peter Perkins 2014-10-2

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https://ww2.mathworks.cn/matlabcentral/answers/156310-setdiff-error-in-some-cases#answer_153643

Neesha, this appears to be a bug when one of the datasets has zero rows and the other has exactly one. A valid edge case to be sure, but somewhat obscure. I will make a note to adress this bug.