When faced with the same value in a vector, what can you do to choose one over the other?

This may be a little hard to explain but I'll try my best.

So I have indexed a 3x1 vector(A) and 3x6 matrix(B) so that the location of the max number in vector A will be the base of location for bringing over all 3 values of A to the designated row that the max number is in. That code looks like

idx1 = (A==max(A));
B(idx1,1:3) = A

So let's say that creates

A = 1
    5
    2
B = NaN NaN NaN NaN NaN NaN
     1   5   2  NaN NaN NaN
    NaN NaN NaN NaN NaN NaN

Now if I had a tie between max numbers, what can I do to randomly create 2 new numbers to replace those same values so that I can do what I just did if there were no double max numbers? Like if A = [5;5;2] I would want to randomly change the two values of 5 into two new values between the value of 1:5 (let's say the former is changed to 1 and the latter is changed to 4). Then the 4 would be the new max number, and all previous coding (from when all values were different) would apply.

What lines of codes would work for this? I have tried a few if statements but none work.

Answer 1

[Stephen23]

I would use randperm:

%A = [1;5;2]
A = [5;5;2]
B = NaN(3,6);
% new code:
idx = A==max(A);
num = nnz(idx);
A(idx) = max(A)-num+randperm(num,num);
% original code:
idy = A==max(A);
B(idy,1:3) = A

Note that this works for one or more maximum values. The code does not randomly pick new values from 1:5 as you ask, but instead uses randperm on the set of values [max,max-1,...]. This is because if the values are randomly picked then there is no guarantee that the new values will not cause multiple new max values, eg:

>> A = [5;5;4];
>> new = [4,1]; % random between 1:5
>> A(A==max(A)) = new
A =
     4
     1
     4

and thus you get back to the same problem as you had at the start. For this reason I used randperm.