Plotting the content of huge matrix.

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Vira Roy 2022-4-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1707850-plotting-the-content-of-huge-matrix

评论： Vira Roy 2022-4-29

Problem: I have a huge 449x10001 dimension matrix and want to make a scatter plot from that. While for loop works good enough for smaller size, plotting this huge matrix is extremely time and resource consuming. (I am aware this is a bad way of coding the problem, sorry)

I have attached a smaller version of the huge matrix here and shown my code below. This code here with matrix dimension 449x50 takes 31 seconds to do the plot. Is there a better way without using a for loop to access the entries and make the plot.

It would be extremely helpful if you can guide someway here. Thank you.

My code(attached are big_mat.mat and yaxis.mat)

x = linspace(1,449,449);
y_ = matfile('yaxis.mat');
spectral_wt = matfile('big_mat.mat');
S_wt = spectral_wt.spectral_wt;
y = y_.y;
for i = 1 : 50
    scatter(x,y(:,i),[],S_wt(:,i),'filled')
    hold on 
    colormap default
    colorbar
    ylabel('Energy')
    xticks([0 64 128 192 256 320 384 448])
    xticklabels({'\Gamma','M1','M2','M3','X1','X2','X3','R'})
    xline([64,128,192,256,320,384,448]);
end 

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Answer 1

KSSV 2022-4-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1707850-plotting-the-content-of-huge-matrix#answer_953495

编辑：KSSV 2022-4-29

在 MATLAB Online 中打开

You need not to use scatter in a loop. You can do all this at one go using scatter or you can use pcolor as shown below.

x = linspace(1,449,449);
y_ = matfile('yaxis.mat');
spectral_wt = matfile('big_mat.mat');
S_wt = spectral_wt.spectral_wt;
y = y_.y;
X = repmat(x,size(y,2),1)' ; 
Y = y ; 
Z = S_wt ; 
pcolor(X,Y,Z)
shading interp 
colormap default
colorbar
ylabel('Energy')
xticks([0 64 128 192 256 320 384 448])
xticklabels({'\Gamma','M1','M2','M3','X1','X2','X3','R'})
xline([64,128,192,256,320,384,448]);