Need help to solve with ncmlogo.m

Question

Jessie Chen 2024-7-6，8:32

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https://ww2.mathworks.cn/matlabcentral/answers/2136843-need-help-to-solve-with-ncmlogo-m

回答： Steven Lord 2024-7-12，15:51

Hello everyone! I am a freshman in MATLAB. When learning ncmlogo.m to picture a logo, I can not solve the problem of change z axis value of Isosurfaces to get them on different planes, but maintains the shape of the isosurface. The source code change the zdata:

L = rot90(membranetx(1,32,10,10),2);

% Filled contour plot with transparent lifted patches

b = (1/16:1/8:15/16)';

for k = 1:8

[c,h(k)] = contourf(L,[b(k) b(k)]);

m(k) = length(get(h(k),'xdata'));

set(h(k),'linewidth',2,'edgecolor','w', ...

'facealpha',.5,'zdata',4*k*ones(m(k),1))

end

But get the error:

Incorrect use of matlab.graphics.chart.primitive.Contour/setZDataImpl

Z must be at least a 2x2 matrix.

Error matlab.graphics.chart.primitive.Contour/set. ZData

Error untitled2 (line 25)

set(h(j), 'ZData', zdata);

Does the zdata have many meanings?

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Answer 1

Steven Lord 2024-7-12，15:51

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2136843-need-help-to-solve-with-ncmlogo-m#answer_1484923

Let's look at the text of the error message.

Incorrect use of matlab.graphics.chart.primitive.Contour/setZDataImpl

Z must be at least a 2x2 matrix.

What are you using to set the Z data of the contour plot in your code?

set(h(k),'linewidth',2,'edgecolor','w', ...

'facealpha',.5,'zdata',4*k*ones(m(k),1))

What is the size of 4*k*ones(m(k), 1)? Does it have at least two rows and at least two columns? If m(k) is 2 or greater then it has at least two rows, but it's only going to have 1 column.

Rather than using length to create the value of m:

m(k) = length(get(h(k),'xdata'));

I think you'll want to use the size of the original Z data of the contour plot to create the new Z data for the contour plot instead.

Alternately, if I understand your description you might want to use either the contourslice function or (if you want to display a surface with the contour levels) maybe surfc.