Help needed adding features to this script.

I have a script (shown below) that will generate a 12x12 matrix of all 0's and a single 1, which will replicate in a randomised order 7200 times. There are three features I want to add to this script but don't know how:

1. Instead of generating a matrix in a complete random order I want digits to move either one place up, down, left or right from their position in the previous matrix.
2. A shortcut that will create an imagesc() for all 7200 matrix's (like the image below).

Any help would be greatly appreciated.

Thanks,

Joe

count=0;
m=zeros(144,1);
rand_int=datasample(1:144,1);
m(rand_int)=1;
old_matrix=reshape(m,[12 12]);
for i=1:7200
    m=zeros(144,1);
    rand_int=datasample(1:144,1);
    m(rand_int)=1;
    new_matrix=reshape(m,[12 12]);
    if sum(abs(old_matrix-new_matrix),'All')>0
        count=count+1;
    end
    old_matrix=new_matrix
end

Answer 1

[Image Analyst]

Here is one way:

m = zeros(12, 12);
numIterations = 7200;
row = ones(1, numIterations);
col = ones(1, numIterations);
m(row(1), col(1)) = 1;
imagesc(m);
axis('on', 'image');
for k = 2 : numIterations
	row(k) = row(k-1) + randi([-1,1], 1);
	while row(k) <= 0 || row(k) > size(m, 1)
		row(k) = row(k-1) + randi([-1,1], 1);
	end
	col(k) = col(k-1) + randi([-1,1], 1);
	while col(k) <= 0 || col(k) > size(m, 2)
		col(k) = col(k-1) + randi([-1,1], 1);
	end
	m(row(k), col(k)) = 1;	% Set new location
	m(row(k-1), col(k-1)) = 0; % Clear old location
	imagesc(m);
	drawnow;
end

[Joseph Lee]

That works great thanks!

Can you think of any way to slow down the image creation? a delay of sorts.

[Image Analyst]

Put in a pause(0.5) to pause the display some time.

m = zeros(12, 12);
numIterations = 7200;
row = ones(1, numIterations);
col = ones(1, numIterations);
m(row(1), col(1)) = 1;
imagesc(m);
axis('on', 'image');
for k = 2 : numIterations
	row(k) = row(k-1) + randi([-1,1], 1);
	while row(k) <= 0 || row(k) > size(m, 1)
		row(k) = row(k-1) + randi([-1,1], 1);
	end
	col(k) = col(k-1) + randi([-1,1], 1);
	while col(k) <= 0 || col(k) > size(m, 2)
		col(k) = col(k-1) + randi([-1,1], 1);
	end
	m(row(k), col(k)) = 1;	% Set new location
	m(row(k-1), col(k-1)) = 0; % Clear old location
	imagesc(m);
	drawnow;
        pause(0.5);
end

[Joseph Lee]

Great thanks!

Also could you tell me why the image will periodically turn a light blue colour and then back. Is this a processing issue due to the number of images being created?

[Image Analyst]

I didn't see that. Occasionally I'd see the screen flicker. Maybe it picks a colormap that's different if the array is all zeros with no ones. You might reverse the clearing and setting to make sure that there is always a 1 there in case it picked the same location:

Change

	m(row(k), col(k)) = 1;	% Set new location
	m(row(k-1), col(k-1)) = 0; % Clear old location

to

	m(row(k-1), col(k-1)) = 0; % Clear old location
	m(row(k), col(k)) = 1;	% Set new location

[Joseph Lee]

Also one final question, is there a way of increasing the percentage chance that the 1 in the matrix wont change position when the matrix replicates? maybe a 1:2 ratio.

Again thanks for your speedy responses.

Joe

[Image Analyst]

Just skip the loop if the probability is less. And if trying a new place, make sure it's not the same as the old place.

m = zeros(12, 12);
numIterations = 7200;
row = ones(1, numIterations);
col = ones(1, numIterations);
m(row(1), col(1)) = 1;
imagesc(m);
axis('on', 'image');
percentage = 0.20; % 20% of time will be the same
for k = 2 : numIterations
	if rand(1) < percentage
                % 20% of the time it will stay in the same place.
		row(k) = row(k-1);
		col(k) = col(k-1);
	else		
		% 80% of the time it will select a new place.
                % First get a tentative new location.
                row(k) = row(k-1) + randi([-1,1], 1);
		col(k) = col(k-1) + randi([-1,1], 1);
                while row(k) == row(k-1) && col(k) == col(k-1)
        		while row(k) <= 0 || row(k) > size(m, 1)
        			row(k) = row(k-1) + randi([-1,1], 1);
        		end
        		while col(k) <= 0 || col(k) > size(m, 2)
        			col(k) = col(k-1) + randi([-1,1], 1);
        		end
                end
	end
	m(row(k-1), col(k-1)) = 0; % Clear old location
	m(row(k), col(k)) = 1;	% Set new location
	imagesc(m);
	grid on;
	caption = sprintf('At Iteration %d, Row = %d, Column = %d', k, row(k), col(k));
	title(caption, 'FontSize', 15);
	drawnow;
	pause(0.4)
end

[Joseph Lee]

I get an error message when I run it and the matrix doesn't change

[Image Analyst]

Sorry, try this (actually tested this time):

m = zeros(12, 12);
numIterations = 7200;
row = ones(1, numIterations);
col = ones(1, numIterations);
m(row(1), col(1)) = 1;
imagesc(m);
axis('on', 'image');
percentage = 0.20; % 20% of time will be the same
for k = 2 : numIterations
	if rand(1) < percentage
		% 20% of the time it will stay in the same place.
		row(k) = row(k-1);
		col(k) = col(k-1);
	else
		% 80% of the time it will select a new place.
		% First get a tentative new location.
		row(k) = row(k-1) + randi([-1,1], 1);
		col(k) = col(k-1) + randi([-1,1], 1);
		while row(k) == row(k-1) && col(k) == col(k-1) || row(k) <= 0 || row(k) > size(m, 1) || col(k) <= 0 || col(k) > size(m, 2)
			% Get a new location.
			row(k) = row(k-1) + randi([-1,1], 1);
			col(k) = col(k-1) + randi([-1,1], 1);
			while row(k) <= 0 || row(k) > size(m, 1)
				row(k) = row(k-1) + randi([-1,1], 1);
			end
			while col(k) <= 0 || col(k) > size(m, 2)
				col(k) = col(k-1) + randi([-1,1], 1);
			end
		end
	end
	m(row(k-1), col(k-1)) = 0; % Clear old location
	m(row(k), col(k)) = 1;	% Set new location
	imagesc(m);
	grid on;
	caption = sprintf('At Iteration %d, Row = %d, Column = %d', k, row(k), col(k));
	title(caption, 'FontSize', 15);
	drawnow;
	% 	pause(0.4)
end

[Joseph Lee]

Great thanks for your help.

Could you tell me how to assign colors to the numbers. white for zero, red for one? Is this possible to do using Colormaps?