How to find indices of similar values in a vector?

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

[Jan]

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.

Answer 1

[Rob Campbell]

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

[Syed Fahad Hassan]

Thanks Rob. This helped