Unique random number (between 1 and 40)

I wish for a vector consisting of 30 numbers. I want those numbers to be between 1 and 40 BUT NOT with the same number appearing more than once.

I have found this:

clear all; close all; clc n=30; number=zeros(1,n); %Generates my vector for i=1:n number(1,i)=ceil(rand()*40); %B = ceil(A) rounds the elements of A to the nearest integers greater %than or equal to A. For complex A, the imaginary and real parts are rounded independently. end

My problems begin when I want to verify that the figure/value/number in number(i) does not exist in any other location (number(:)) and IF it does, I want it to give me a new random number.

I have attempted every sort of if-for-while-loops, added within the initial loop as well as applied onto the generated number-vector, I can think of and I either get syntax errors or a neatly looking code that does not do what I want.

I would be most grateful for help.

/Josefine

Answer 1

[Wayne King]

Why not just use randperm()

x = randperm(40);

If you want to randomly select a subset

K = 10;
x = randperm(40,K);

[Josefine]

I also just found this, which seems to work better for my version of MATLAB

 n=40;
 k=30;
 [idx,idx]=sort(rand(1,n));
 out=idx(1:k)

[Parisa]

Hi, your code help me a lot, thanks