Alternative to 'ismember' for structures

Question

Enrico Anderlini 2016-8-26

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https://ww2.mathworks.cn/matlabcentral/answers/300969-alternative-to-ismember-for-structures

评论： Enrico Anderlini 2016-8-26

Hello! I have a structure, which I need to update at every step. However, I would like to include the update only if it has not been stored yet. This would be quite easy with a list and ismember. However, ismember does not work with structures. Has anyone got any suggestions? Thank you!

As an example, for greater clarity, consider the following problem:

A.a = 1;
A.b = 2;
A(2).a = 2;
A(2).b = 3;
A(3).a = 3;
A(3).b = 4;
B.a = 2;
B.b = 3;

Now, it is clear that B is contained within A (line 2, or B=A(2)).

If they were lists, I would use the command:

ismember(B,A,'rows);

What can I do if I would like to keep them as structures? Thank you!

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Answer 1

Adam 2016-8-26

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https://ww2.mathworks.cn/matlabcentral/answers/300969-alternative-to-ismember-for-structures#answer_232835

在 MATLAB Online 中打开

any( arrayfun( @(x) isequal( B, x ), A ) )

should do the job I think.

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Enrico Anderlini 2016-8-26

It does exactly what I need it to do. Thanks!

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Answer 2

Azzi Abdelmalek 2016-8-26

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/300969-alternative-to-ismember-for-structures#answer_232830

在 MATLAB Online 中打开

You can compare

ismember([B.a],[A.a])
ismember([B.b],[A.b])

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Enrico Anderlini 2016-8-26

Thank you! Your answer works too and it employs ismember. However, the other answer is more compact and results in a single boolean, which is what I needed to start with.

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