How to collect the outputs and then plot them

Question

Zeinab Ahmadi93 2017-7-6

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/347638-how-to-collect-the-outputs-and-then-plot-them

评论： Walter Roberson 2017-7-7

Hello I want to plot that is created by the following function,How can I do it? A person who has written the code has also written the following sentences below it but I don't understand his meaning. "You should collect the outputs (e.g. [x1,y1,x2,y2] = q44916610()) and then plot them yourself however you like. The plotting within the function is animated, which is going to take additional time for no reason."

function [x,y,xi,yi] = q44916610(doPlot)
    %%Input handling:
    if nargin < 1 || isempty(doPlot)
      doPlot = false;
    end
    %%Initialization:
    origin = [50,50];
    vertspacing = 10;
    thetamax = 5*(2*pi);
    %%Calculation of (x,y) - underlying archimedean spiral.
    b = vertspacing/(2*pi);
    theta = 0:0.01:thetamax;
    x = b*theta.*cos(theta) + origin(1);
    y = b*theta.*sin(theta) + origin(2);
    %%Calculation of equidistant (xi,yi) points on spiral.
    DST = 5; cRes = 360; 
    numPts = ceil(vertspacing*thetamax); % Preallocation
    [xi,yi] = deal(NaN(numPts,1));
      if doPlot && isHG2() % Plots are only enabled if the MATLAB version is new enough.
        figure(); plot(x,y,'b-'); hold on; axis equal; grid on; grid minor;
        hAx = gca; hAx.XLim = [-5 105]; hAx.YLim = [-5 105];
        hP = plot(xi,yi,'r*');
      else
        hP = struct('XData',xi,'YData',yi);
      end
      hP.XData(1) = origin(1); hP.YData(1) = origin(2);
      for ind = 2:numPts
        P = InterX([x;y], makeCircle([hP.XData(ind-1),hP.YData(ind-1)],DST/2,cRes));  
        [~,I] = max(abs(P(1,:)-origin(1)+1i*(P(2,:)-origin(2))));
        if doPlot, pause(0.1); end
        hP.XData(ind) = P(1,I); hP.YData(ind) = P(2,I);
        if doPlot, pause(0.1); delete(hAx.Children(1)); end
      end
      xi = hP.XData(~isnan(hP.XData)); yi = hP.YData(~isnan(hP.YData));
      %%Nested function(s):
      function [XY] = makeCircle(cnt, R, nPts)
        P = (cnt(1)+1i*cnt(2))+R*exp(linspace(0,1,nPts)*pi*2i);
        if doPlot, plot(P,'Color',lines(1)); end
        XY = [real(P); imag(P)];
      end
      end
      %%Local function(s):
      function tf = isHG2()
        try
          tf = ~verLessThan('MATLAB', '8.4');
        catch
          tf = false;
        end
      end
      function P = InterX(L1,varargin)
          % DOCUMENTATION REMOVED. For a full version go to:
          % https://www.mathworks.com/matlabcentral/fileexchange/22441-curve-intersections
          narginchk(1,2);
          if nargin == 1
              L2 = L1;    hF = @lt;   %...Avoid the inclusion of common points
          else
              L2 = varargin{1}; hF = @le;
          end
          %...Preliminary stuff
          x1  = L1(1,:)';  x2 = L2(1,:);
          y1  = L1(2,:)';  y2 = L2(2,:);
          dx1 = diff(x1); dy1 = diff(y1);
          dx2 = diff(x2); dy2 = diff(y2);
          %...Determine 'signed distances'   
          S1 = dx1.*y1(1:end-1) - dy1.*x1(1:end-1);
          S2 = dx2.*y2(1:end-1) - dy2.*x2(1:end-1);
          C1 = feval(hF,D(bsxfun(@times,dx1,y2)-bsxfun(@times,dy1,x2),S1),0);
          C2 = feval(hF,D((bsxfun(@times,y1,dx2)-bsxfun(@times,x1,dy2))',S2'),0)';
          %...Obtain the segments where an intersection is expected
          [i,j] = find(C1 & C2); 
          if isempty(i), P = zeros(2,0); return; end
          %...Transpose and prepare for output
          i=i'; dx2=dx2'; dy2=dy2'; S2 = S2';
          L = dy2(j).*dx1(i) - dy1(i).*dx2(j);
          i = i(L~=0); j=j(L~=0); L=L(L~=0);  %...Avoid divisions by 0
          %...Solve system of eqs to get the common points
          P = unique([dx2(j).*S1(i) - dx1(i).*S2(j), ...
                      dy2(j).*S1(i) - dy1(i).*S2(j)]./[L L],'rows')';
          function u = D(x,y)
              u = bsxfun(@minus,x(:,1:end-1),y).*bsxfun(@minus,x(:,2:end),y);
          end
      end

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Answer 1

KSSV 2017-7-7

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/347638-how-to-collect-the-outputs-and-then-plot-them#answer_273175

在 MATLAB Online 中打开

It is clearly mentioned that, if you input 1 to the function it will do animation, if the input is empty it will not do animation. See the below code which runs the function and plots the output obtained.

[x,y,xi,yi] = q44916610() ;
 figure
 hold on
 plot(X,y,'r') ;
 plot(xi,yi,'*b') ;

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Zeinab Ahmadi93 2017-7-7

编辑：Zeinab Ahmadi93 2017-7-7

MGwfy.gif

Thanks it works. Another question, It shows the plot but the star markers don't traverse along the trajectory and are just fixed. How can I change it in order to show a figure like "MGwfy.gif"?