How do I combine multiple plots in a for loop?

Hello all,

I am trying to plot within a for loop, but it only plots the last value, as it's overwritting previous values. My code look like the following:

BLOCK = 5x1 cell array
TIME = 5x1 cell array

for i=length(BLOCK)
plot(TIME(i),BLOCK(i))
end

Not sure how to get this, so it doesn't overwrite previous values. Thank you

[Azzi Abdelmalek]

Christopher commented

I am trying to change the color for each i iteration though. This works, but gives me the same color plot for every iteration.

Answer 1

[Jonathan LeSage]

Add “hold on” prior to your for-loop.

Adding a "hold on" command means that anything that you plot will not clear the existing graph, but just plot on top of what is already there. You can turn off this functionality with the "hold off" command.

for k = 1:length(BLOCK)
    plot(TIME(k),BLOCK(k))
    if k == 1
       hold on
    end
end
hold off

[Christopher]

That worked, but I was trying to change the color for each i. So BLOCK{1} would be say blue, BLOCK{2} would be green, etcc.

[Jonathan LeSage]

Is the colormap method I suggested in my edit what you are looking for?

[Christopher]

Thank you Jonathan, that is exactly what I was looking to do. I have accepted your answer. Thanks to everyone else for there responses as well.

[Rik]

Comment mistakenly posted as flag by AISWARYA LAKSHMI:

This code did not work for me! Only an empty plot screen appears :/

Answer 2

[dpb]

hold on

after first.

Answer 3

[Hem Zaveri]

I needed to plot graph of frames Vs pixel difference. And the plot was supposed to be inside the for loop. So after seeing this answer I solved one issue, that i update the graph using update. But i want all the points to be connected. Can you help me with it ?

Here is my code

for f = startingFrame+1 : finalFrame
  frame = aviread(inFile, f);
  i2 = frame.cdata; %cdata — The image data stored as a matrix of uint8 values. The dimensions of F.cdata are height-by-width-by-3.
  ig2 = rgb2gray(i2);
  [c2,n2] = imhist(ig2);
  c2=c2/size(ig2,1)/size(ig2,2);
  d = pdist2(c1',c2','cityblock');
  if (d > 0.2150)  %%change the threshold

        c1 = c2;
       m = im2frame(i2);
       mov = addframe(mov,m);
       pause(1/FPS);

    end
    disp(d);
   hold on;
   axis([1 95 0.16 0.26]);
    plot(f,d,'--rs','LineWidth',2,...
                'MarkerEdgeColor','k',...
                'MarkerFaceColor','g',...

                'MarkerSize',10);
end

f = frame, d = pixel difference which lies between 0.16 - 0.26 </matlabcentral/answers/uploaded_files/20313/asd.PNG>

[ang yong qin]

Maybe you can store the data in a matrix first before plotting the points all together.