Generate a random logical vector of a given size with a given number of true values?

How can I generate random logical vector with the set number of true values?

E.g. I want a vector with 10 elements that has 7 true values:

[1 1 1 0 0 1 1 0 0 0]

[1 1 0 1 0 1 1 0 0 0]

...

I tried something like:

random_num = zeros(1,10); % generates vector of 10 zero values
num_true_val = 7; % wanted number of true values
Sum = sum(random_num);
while Sum<num_true_val
        position = randi([1 width(random_num)],1,1); % generate random position btw 1 and 10
        random_num(1,position) = 1; % pin value of 1 to that position
        Sum = sum(random_num); % calc sum again
        random_num = logical(random_num)
end
disp(random_num)

     1     0     0     1     1     1     0     1     1     1

This does the job but seems too long and I feel like there might be a better solution.

Answer 1

[Jiri Hajek]

Hi, ince the number of true values is known beforehand, the problem may be translated as just picking random positions, where to place them. This may be easily done using randi function:

N = 10; % generates vector of 10 zero values
random_num = zeros(1,N); % initialize with zeros
num_true_val = 7; % wanted number of true values
random?num(randi(N,1,num_true_val)) = 1; 

[Ela Markovic]

Thank you for your input.

Your solution doesn't work because randi can select one value twice.

But if I switch randi for randperm then it works! Thank you, your solution is really simple.

So the final would be:

N = 10; % generates vector of 10 zero values
random_num = zeros(1,N); % initialize with zeros
num_true_val = 7; % wanted number of true values
random_num(randperm(N,num_true_val)) = 1; 

[Jiri Hajek]

Sorry for that glitch. You deserve the credit.