MATLAB: How select random elements of array without replacement

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I have a matrix A(1*N).[a11 a12 a13 a14 a15 a16 a17 …..] first,I want to select random m1 member of A without replacement .then I want to select m2 member without replacement that don't select befor step. and I want that don't select a14 in any step. can anybody help me to write matlab code of it?

Best Answer

The easiest way to do this is to use randperm: this provides a random selection without replacement. Note that randi uses replacement, so is not useful for your task.
Something like this:
>> A = 1:23;
>> excl = 4; % indices to exclude
>> B = A(~ismember(1:numel(A),excl));
>> idx = randperm(numel(B));
Where B contains all values of A except the elements at locations given in excl, and idx contains random indices without replacement for every element in B. Thus you can easily use these indices in a loop:
for k = 1:numel(B)
    B(idx(k))
end
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