logical vector equality

Question

Truman 2011-7-2

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https://ww2.mathworks.cn/matlabcentral/answers/10767-logical-vector-equality

Often I run into a situation where I need to determine if two vectors are equal and do something if they are. However, vec1==vec2 gives me a vector - not a logical 0 or 1. So I have to mess with that and it seems that Matlab should be able to tell me if two vectors or even structures are equal. However, I am not smart enough to figure how to make it do that without writing extra code every time it arises.

My question is how to I get a 0 or 1 result from v1==v2 when they are vectors?

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Answer 1

Paulo Silva 2011-7-2

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在 MATLAB Online 中打开

all(vec1==vec2)

and if you want to ignore the difference between column and row vectors do

all(vec1(:)==vec2(:))

There's also this way to compare

isequal(vec1,vec2)

With the isequal you don't have the problem with the dimensions mismatch like you have with the case vec1==vec2

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Matt Fig 2011-7-2

In addition to what Paulo says, IF statements automatically use ALL for vector conditionals. For example:

A = [1 2 3 4];

B = A;

if A==B

disp('InIF')

end

But now:

B(4) = 7;

if A==B

disp('InIF')

end

So if you know A and B will always have the same size and type, using == with an IF statement is fine. However, if there is any doubt about size or type, ISEQUAL is preferred.

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