How to find indices of similar values in a vector?

Asked by Syed Fahad Hassan on 1 Aug 2017

Latest activity Commented on by Syed Fahad Hassan on 1 Aug 2017

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I want to get the indices of similar values in a vector. For example, I have a vector x=[1 1 2 2 3]. The output should be something like this: indices = 1,2 & 3,4

1 Comment

Jan on 1 Aug 2017

Duplicate question, see https://www.mathworks.com/matlabcentral/answers/351130-how-to-find-indices-of-similar-elements-in-a-vector

@Syed Fahad Hassan: Please post a question only once.

1 Answer

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Answer by Rob Campbell on 1 Aug 2017

Edited by Rob Campbell on 1 Aug 2017

Accepted Answer

I'm unsure if you're looking for sequential numbers or not. The following just looks for repeats. Does it do what you want?

x = [1,1,2,2,3,4,5,6,1,2,3];
% Store in a cell array the indexes of values that repeat
reps={};
for thisU=unique(x)
     f=find(x==thisU);
     if length(f)>1, reps{end+1}=f; end
end

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Syed Fahad Hassan on 1 Aug 2017

Thanks Rob. This helped

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