Error using randi Size inputs must be scalar (Matlab)

I have entries parameters A and B, and I have to obtain C with for loop, where C is the random subset of B of size Ai

I program this

for i=1:n

C=randi([0,1],B,A(i));

end

But I get the error (Error using randi ==> inputs must be scalar)

How can I fixe the problem

[Rik]

How are you making sure B and A(i) are positive scalars?

Answer 1

[Jan]

"C is the random subset of B of size Ai" :

for i = 1:n
  % Without repetitions:
  C = B(randperm(numel(B), A(i)));
  
  % Or with repetitions:
  C = B(randi([1, numel(B)], 1, A(i)));
  
  ... use C now
end

[high speed]

@Jan What do you mean by repetitions

[Rik]

If you have an array with these values:

B=[3 6 9];

Now you can take random samples in two ways:

C=[6 3 6]
%or
C=[6 9 3]
%or
C=[3 3 3]
%or
...

Or like this:

C=[3 6]
%or
C=[3 9]
%or
C=[9 6]

[Jan]

@high speed: Simply try it:

B = 1:4;

% No repetitions:
C = B(randperm(numel(B), 4))
C = B(randperm(numel(B), 4))
C = B(randperm(numel(B), 4))
C = B(randperm(numel(B), 4))
  
% With repetitions:
C = B(randi([1, numel(B)], 1, 4));
C = B(randi([1, numel(B)], 1, 4));
C = B(randi([1, numel(B)], 1, 4));
C = B(randi([1, numel(B)], 1, 4));

Do you see it? With repetitions the values in the output can repeat. Then C can be longer than B. Without repetition, C is a permutation of the elements of B.

[high speed]

@Jan Unfortunately, that's not what I want. Because I must program in a way that C is the random subset of B of size Ai. And in your example you didn't consider the size Ai

[Jan]

@high speed: Sorry, what? Yes, in my example, I've used 4 to clarify what "repetition" means. You have asked for this detail. But the code in my answer does contain A(i).