Find same numbers in two vectors

Question

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Hello,

i need to find same numbers in two vectors and write them down in a third one. Example:

a = [3,8,10,11]
b = [2,3,10,12]

The result should be this vector:

result = [3,10]

Do you have an idea how to do this?

Thanks

Robert

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Answer 1

Johannes Fischer 2021-6-2

0 个投票

I think what you need is the ismember function:

a = [3,8,10,11]
b = [2,3,10,12]
result = a(ismember(a, b))
% or
result = b(ismember(b, a))

Thank you very much!!

Johannes Fischer 2021-6-2

Keep in mind that the results will be different, when a number occurr multiple times

a = [3,8,10,11,3];
b = [2,3,10,10,12];
resultA = a(ismember(a, b))
resultB = b(ismember(b, a))

leads to

resultA =
     3    10     3
resultB =
     3    10    10     

You can avoid this using unique:

resultA = unique(a(ismember(a, b)))
resultB = unique(b(ismember(b, a)))

will lead to

resultA =
     3    10
resultB =
     3    10