Matlab Code to distribute points on plot - matlab

Question

I have edited a code that i found online that helps me draw points somehow distributed on a graph based on the minimum distance between them
This is the code that i have so far
x(1)=rand(1)*1000; %Random coordinates of the first point
y(1)=rand(1)*1000;
minAllowableDistance = 30; %IF THIS IS TOO BIG, THE LOOP DOES NOT END
numberOfPoints = 300; % Number of points equivalent to the number of sites
keeperX = x(1); % Initialize first point
keeperY = y(1);
counter = 2;
for k = 2 : numberOfPoints %Dropping another point, and checking if it can be positioned
done=0;
trial_counter=1;
while (done~=1)
x(k)=rand(1)*1000;
y(k)=rand(1)*1000;
thisX = x(k); % Get a trial point.
thisY = y(k);
% See how far is is away from existing keeper points.
distances = sqrt((thisX-keeperX).^2 + (thisY - keeperY).^2);
minDistance = min(distances);
if minDistance >= minAllowableDistance
keeperX(k) = thisX;
keeperY(k) = thisY;
done=1;
trial_counter=trial_counter+1;
counter = counter + 1;
end
if (trial_counter>2)
done=1;
end
end
end
end
So this code is working fine, but sometimes matlab is freezing if the points are above 600. The problem is full , and no more points are added so matlab is doing the work over and over. So i need to find a way when the trial_counter is larger than 2, for the point to find a space that is empty and settle there.
The trial_counter is used to drop a point if it doesn't fit on the third time.
Thank you

Answer 1

Since trial_counter=trial_counter+1; is only called inside if minDistance >= minAllowableDistance, you will easily enter an infinite loop if minDistance < minAllowableDistance (e.g. if your existing points are quite closely packed).
How you do this depends on what your limitations are, but if you're looking at integer points in a set range, one possibility is to keep the points as a binary image, and use bwdist to work out the distance transform, then pick an acceptable point. So each iteration would be (where BW is your stored "image"/2D binary matrix where 1 is the selected points):
D = bwdist(BW);
maybe_points = find(D>minAllowableDistance); % list of possible locations
n = randi(length(maybe_points)); % pick one location
BW(maybe_points(n))=1; % add it to your matrix
(then add some checking such that if you can't find any allowable points the loop quits)