Plot animation Effcientcey and double to struct error

Question

Lawson Hoover 2012-12-8

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/56076-plot-animation-effcientcey-and-double-to-struct-error

I am trying to animate a plot. I have got it to work but I seems to moving a tad slow, and Also when I allocate the frames into a variable M with getframe, the M gets a red underline saying that I should preallocate for speed. I have been trying to do this but I get is the error:

   The following error occurred converting from struct to double:
  Error using double
  Conversion to double from struct is not possible.

I have no idea how to fix this. The code I am using is below:

   plot(x,y,'--r','LineWidth',3);  % original position
  xlabel('Beam Length (in.)','Color','g');
  ylabel(bstr,'Color','g');
  ylim([-(Beam.y(10)) max(Beam.y)]);
  title(astr,'Color','y','fontweight','b');
  set(S.ax,'YDir','reverse');
  set(S.ax,'XGrid','on');
  set(S.ax,'YGrid','on');
  y =0;
  z = 0;
  hold on 
  clear M
  M = zeros(1,100);
  ht = plot(y,z,'-b','linewidth',2); % new position
  for i = 1:100
    if i == 1
        set(ht ,'XDataSource','Beam.x')
        set(ht,'YDataSource','Beam.y')
    end
  set(ht,'XData',Beam.x(1:i))
  set(ht,'YData',Beam.y(1:i))
  M(i) = getframe(gcf);   % this says that I shoudld preallocate it but when I do I get an error
  end
  legend('Without Deflection','With Deflection');
  hold off

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Answer 1

Walter Roberson 2012-12-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/56076-plot-animation-effcientcey-and-double-to-struct-error#answer_67922

getframe() returns a movie frame, which is a struct. You cannot store a struct into a scalar double location such as M(i) where M has been initialized to zeros(1,100)

http://www.mathworks.com/help/matlab/ref/getframe.html

What are you going to do with the frames after you get them? If you are going to create a video, then see the documentation for VideoWriter for an example of how to do it.