How to randomly swap 2 elements in an array?

I'm going to assume at least one of the swap elements must be an number, and that the swapped numbers are allowed to have the same value (so you can some one 9 with another 9).

C=  [1     6     5    10     1     2    11     8     2     7     3     7     9     9];
bold=[1 5 6 9 10 12 13 14];
C_temp=cell(1,2*numel(C));
C_temp(2:2:end)=num2cell(C);
valid_idx=1:numel(C_temp);
valid_idx(bold*2)=[];
swap_idx=[1 1];%invalid output to enter the loop
while ~any(mod(swap_idx,2)==0) || ... %at least 1 needs to be a number
        swap_idx(1)==swap_idx(2) %the indices must be different
    swap_idx=valid_idx(randperm(numel(valid_idx),2));
end
%perform swap
C_temp(swap_idx)=C_temp(swap_idx(end:-1:1));
D=cell2mat(C_temp);
clc,disp(C),disp(D)

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Rik 2019-5-4

在 MATLAB Online 中打开

This should prevent the two swapped values to be adjacent (which swaps a value with a gap, meaning it seems the array stays the same).

while ~any(mod(swap_idx,2)==0) || ... %at least 1 needs to be a number
        any(swap_idx==1) || ... %the first element (1 before the first number) isn't allowed
        abs(diff(swap_idx))<=1 %the indices must be different and more than 1 appart
    swap_idx=valid_idx(randperm(numel(valid_idx),2));
end