SURF plot: Data dimensions must agree

Question

Azeem Singh Kahlon 2020-5-25

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https://ww2.mathworks.cn/matlabcentral/answers/532468-surf-plot-data-dimensions-must-agree

评论： Hélène Parisot-Dupuis 2023-11-28

I am trying to plot the magnetic field on a rectangular surface (having x and y coordinates). Hence i have a total of 3 values x,y and B (magnetic field). I have tried plotting the surface plot using normal and transposed datasheet in excel but both of them give me the same data dimensions error. Please help me withi this. I am using the following code till now:

dataset=xlsread('import.xlsx');
x = dataset(:,1);
y = dataset(1,:) 
Z = dataset(2:end,2:end)
surf(x,y,Z)   

Please see the attached image for clarification.

thank you

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Answer 1

Walter Roberson 2020-5-25

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https://ww2.mathworks.cn/matlabcentral/answers/532468-surf-plot-data-dimensions-must-agree#answer_437883

在 MATLAB Online 中打开

dataset=xlsread('import.xlsx');
x = dataset(2:end,1);
y = dataset(1,2:end);
Z = dataset(2:end,2:end);
surf(x, y, Z.', 'edgecolor', 'none')

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Walter Roberson 2020-5-25

Notice also the transpose I do on Z.

Azeem Singh Kahlon 2020-5-25

yes I see that (Z.). However, I do not understand its significance because "Z." and "Z" give the same results.

Thank you once again

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Answer 2

Hélène Parisot-Dupuis 2023-11-28

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https://ww2.mathworks.cn/matlabcentral/answers/532468-surf-plot-data-dimensions-must-agree#answer_1361292

编辑：Walter Roberson 2023-11-28

在 MATLAB Online 中打开

Hello,

I have the kind of problem with my code and I don't understand why:

for it=1:2
    xt(it,1)=it
    for jt=1:3
        yt(1,jt)=jt
        zt(it,jt)=it+(jt-1)
    end
end
xt = 1
yt = 1
zt = 1
yt = 1×2
     1     2
zt = 1×2
     1     2
yt = 1×3
     1     2     3
zt = 1×3
     1     2     3
xt = 2×1
     1
     2
yt = 1×3
     1     2     3
zt = 2×3
     1     2     3
     2     0     0
yt = 1×3
     1     2     3
zt = 2×3
     1     2     3
     2     3     0
yt = 1×3
     1     2     3
zt = 2×3
     1     2     3
     2     3     4
figure;
surf(xt,yt,zt,'EdgeColor', 'None', 'facecolor', 'interp');
Error using surf
Data dimensions must agree.
view(2);
colormap(jet(256));
c = colorbar;

Could you help me to find my error please?

Thanks in advance!

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Walter Roberson 2023-11-28

There are two competing standards for array notation.

When using x and y coordinates, western mathematics tends to put the x first (as rows) and then the y (as columns) -- so in terms of standard Cartesian coordinates, horizontal distance first then vertical distance
When using tables of data, such as a table of costs or a table of trigonmetric values, western mathematics tends to refer to row first and then column -- for example you would look on the row for 1983 and then the column for month -- so vertical distance listed first and then horizontal distance

Any programming language that choses one particular representation (rows mean horizontal distance, rows mean vertical distance) will fail on the other one. So the problem is not a "bug" in MATLAB, or a "mis-design": the problem is competing conventions that cannot both be satisfied.

Hélène Parisot-Dupuis 2023-11-28