random position within a sequare

Hello;

I have a a number of users N and I want to randomly distribute them over a square range of [-10,10]. I used the random function but most of the point end up at the same line. Also, I need to distribute r users near to specific N users with specific distance (between chosen N and r). Can any one explain for me how could I do this?

Thank you in advance.

Answer 1

[Aditya]

Hi m h,

In order to achieve this, you can follow the below steps:

1. Generate random positions for N users within the square range [-10,10] using the rand() function.

N = 10; % Number of users 
range = [-10, 10]; % Square boundary 

% Generate random positions in 2D space 
X_N = range(1) + (range(2) - range(1)) * rand(N,1); 
Y_N = range(1) + (range(2) - range(1)) * rand(N,1); 

2. Randomly select r users from N to determine which users will have nearby companions.

r = 5; % Number of nearby users 
selected_idx = randperm(N, r); % Select r random indices 

3. Generate a random angle for each r user to ensure random placement around its paired N user.

angles = 2 * pi * rand(r,1); % Generate random angles between 0 and 2π 

4. Place each r user at a specific distance using cos(angle) and sin(angle)

specific_distance = 2; % fixed distance 
X_r = X_N(selected_idx) + specific_distance * cos(angles); % Shift X
Y_r = Y_N(selected_idx) + specific_distance * sin(angles); % Shift Y 

5. Check minimum distance constraint from all N users to avoid overlap. (You can update this constraint based on the requirement)

for i = 1:r
    for j = 1:N
        if j ~= selected_idx(i)
            dist = sqrt((X_r(i) - X_N(j))^2 + (Y_r(i) - Y_N(j))^2);
            if dist < specific_distance % If too close, regenerate position
                angle = 2 * pi * rand();
                X_r(i) = X_N(selected_idx(i)) + specific_distance * cos(angle);
                Y_r(i) = Y_N(selected_idx(i)) + specific_distance * sin(angle);
            end
        end
    end
end

6. Plot both N and r users distinctly

figure; hold on;

scatter(X_N, Y_N, 50, 'b', 'filled'); % N users (blue)

scatter(X_r, Y_r, 50, 'r', 'filled'); % r users (red)

legend('N Users', 'r Users (Fixed Distance)');
xlabel('X');
ylabel('Y');
title('Randomly Distributed Users with specific Distance');
grid on;
hold off;

I hope this helps!