Is it possible to increase the performance by representing the values of the variables in each iteration of the loop?

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Izan Segarra 2019-2-28

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评论： Izan Segarra 2019-3-1

I'm doing a genetic algorithm to solve the TSP problem and I'm trying to plot the result in each iteration, but I'm obtaining a bad performance. I would like to know how to improve the code to achieve better efficiency.

Is it possible to increase the performance by representing the values of the variables in each iteration of the loop?

  while iga<maxit
      
    %.......
    
    iga=iga+1; %      
    rte = pop(1,:); %Best Route
    
    subplot(1,2,1)
    plot(model.x(rte),model.y(rte),'r','Marker','o','MarkerEdgeColor','black', 'MarkerFaceColor','white','MarkerSize',12);
    title(sprintf('Total Distance = %1.2f, Iteration = %d',cost(1),iga)); 
    
    vxlabels = arrayfun(@(n) {sprintf('%d', n)}, (1:length(model.dt.Points))'); %Number of each point
    Hpl = text(model.x, model.y, vxlabels, 'FontWeight', 'bold', 'HorizontalAlignment',...
    'center', 'BackgroundColor', 'none','FontSize',10)
    
    subplot(1,2,2)
    plot((1:iga-1),minc(1:iga-1),(1:iga-1),meanc(1:iga-1));
    title('Convergence');
    
    drawnow limitrate;
    
    %.......
    
  end

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Walter Roberson 2019-2-28

If you are talking about graphics performance, then you could plot less often, or you could improve the code for doing the plotting.

But perhaps you are talking about the performance of your GA algorithm in the sense of it taking a long time per iteration, or in the sense of it taking a long time to make useful improvements in position?

Izan Segarra 2019-2-28

I am talking about graphics performance.

Without representing the algorithm it takes 2 seconds, however with the representation it takes 110 seconds

I don't know how can I improve the code for doing the plot with better performance.

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Answer 1

Walter Roberson 2019-3-1

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/447585-is-it-possible-to-increase-the-performance-by-representing-the-values-of-the-variables-in-each-itera#answer_363249

在 MATLAB Online 中打开

ax1 = subplot(1,2,1);
ax2 = subplot(1,2,2);
linehandle1 = line(ax1, nan, nan, 'r', 'Marker', 'o', 'MarkerEdgeColor', 'black', 'MarkerFaceColor', 'white', 'MarkerSize', 12);
Hpl = [];
title1 = title('Total Distance and iteration');
linehandle2a = line(ax2, nan, nan);
linehandle2b = line(ax2, nan, nan);
title(ax2, 'Convergence');
while iga<maxit
      
    %.......
    
    iga=iga+1; %      
    rte = pop(1,:); %Best Route
    
    set(linehandl1, 'XData', model.x(rte), 'YData', model.y(rte));
    set(title1, 'string', sprintf('Total Distance = %1.2f, Iteration = %d',cost(1),iga)); 
    
    vxlabels = arrayfun(@(n) {sprintf('%d', n)}, (1:length(model.dt.Points))'); %Number of each point
    if ~isempty(Hpl); delete(Hpl); end
    Hpl = text(model.x, model.y, vxlabels, 'FontWeight', 'bold', 'HorizontalAlignment',...
    'center', 'BackgroundColor', 'none','FontSize',10)
    
    set(linehandle2a, 'XData', 1:iga-1, 'YData', minc(1:iga-1));
    set(linehandle2b, 'XData', 1:iga-1, 'YData', meanc(1:iga-1));
    
    drawnow limitrate;
    
    %.......
    
end

Although it might in theory be more efficient to update all of the text objects rather than creating new ones, there is one text object per label and so changing them all becomes a bit messier. It is possible even without loop, but it involves some advanced features.

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Walter Roberson 2019-3-1

在 MATLAB Online 中打开

ax1 = subplot(1,2,1);
ax2 = subplot(1,2,2);
linehandle1 = line(ax1, nan, nan, 'r', 'Marker', 'o', 'MarkerEdgeColor', 'black', 'MarkerFaceColor', 'white', 'MarkerSize', 12);
Hpl = text(model.x, model.y, {}, 'FontWeight', 'bold', 'HorizontalAlignment',...
    'center', 'BackgroundColor', 'none','FontSize',10);
title1 = title('Total Distance and iteration');
linehandle2a = line(ax2, nan, nan);
linehandle2b = line(ax2, nan, nan);
title(ax2, 'Convergence');
while iga<maxit
      
    %.......
    
    iga=iga+1; %      
    rte = pop(1,:); %Best Route
    
    set(linehandl1, 'XData', model.x(rte), 'YData', model.y(rte));
    set(title1, 'string', sprintf('Total Distance = %1.2f, Iteration = %d',cost(1),iga)); 
    
    vxlabels = num2str(rte(:));
    set(Hpl, {'String'}, vxlabels);
    
    set(linehandle2a, 'XData', 1:iga-1, 'YData', minc(1:iga-1));
    set(linehandle2b, 'XData', 1:iga-1, 'YData', meanc(1:iga-1));
    
    drawnow limitrate;
    
    %.......
    
end