contour plot problem Z must be at least a 2x2 matrix

Question

Jialin Men 2024-7-25，16:18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2140231-contour-plot-problem-z-must-be-at-least-a-2x2-matrix

评论： Star Strider 2024-7-25，21:25

Hallo everyone,

i have a problem to make the contour plot, it always shows Z must be at least a 2x2 matrix. i have try my best to solve, but it still not work, could you please to help me? The code is as follows.

x=[80;100;90;90;90]
x = 5x1
    80
   100
    90
    90
    90
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<mw-icon class=""></mw-icon>
y=[4;4;2;6;4]
y = 5x1
     4
     4
     2
     6
     4
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
[X,Y] = meshgrid(x,y)
X = 5x5
    80   100    90    90    90
    80   100    90    90    90
    80   100    90    90    90
    80   100    90    90    90
    80   100    90    90    90
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
Y = 5x5
     4     4     4     4     4
     4     4     4     4     4
     2     2     2     2     2
     6     6     6     6     6
     4     4     4     4     4
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
% Polly 11 f(x,y)=p00+p10*x+p01*y
f1=1.7419-0.0006*x+0.0132*y
f1 = 5x1
    1.7467
    1.7347
    1.7143
    1.7671
    1.7407
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
contour(X,Y,f1)
Error using contour (line 48)
Z must be at least a 2x2 matrix.

Thanks and best regards

JL

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Answer 1

Star Strider 2024-7-25，16:34

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链接

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https://ww2.mathworks.cn/matlabcentral/answers/2140231-contour-plot-problem-z-must-be-at-least-a-2x2-matrix#answer_1490686

在 MATLAB Online 中打开

Anotther option, using the scatteredInterpolant function —

x=[80;100;90;90;90]

x = 5x1

80 100 90 90 90

y=[4;4;2;6;4]

y = 5x1

4 4 2 6 4

[X,Y] = meshgrid(x,y);

X = 5x5

80 100 90 90 90 80 100 90 90 90 80 100 90 90 90 80 100 90 90 90 80 100 90 90 90

Y = 5x5

4 4 4 4 4 4 4 4 4 4 2 2 2 2 2 6 6 6 6 6 4 4 4 4 4

% Polly 11 f(x,y)=p00+p10*x+p01*y

f1=1.7419-0.0006*x+0.0132*y

f1 = 5x1

1.7467 1.7347 1.7143 1.7671 1.7407

Fz = scatteredInterpolant(x, y, f1)

Fz =

scatteredInterpolant with properties: Points: [5x2 double] Values: [5x1 double] Method: 'linear' ExtrapolationMethod: 'linear'

F1 = Fz(X,Y)

F1 = 5x5

1.7467 1.7347 1.7407 1.7407 1.7407 1.7467 1.7347 1.7407 1.7407 1.7407 1.7203 1.7083 1.7143 1.7143 1.7143 1.7731 1.7611 1.7671 1.7671 1.7671 1.7467 1.7347 1.7407 1.7407 1.7407

contour(X,Y,F1)

.

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Star Strider 2024-7-25，18:03

在 MATLAB Online 中打开

My pleasure!

I am not certain what you want. The image is of a surfc plot, with additional contour offsets using ZLocation. (I was not aware that more than one was possible, however it could be using the hold function as well. I have never tried that.)

As for setting specific contours, you can do that by selecting LevelList, however with a surfc plot, you would need to do that in a handle to the plot.

That would go something like this —

[X,Y,Z] = peaks;

figure

hsc1 = surfc(X, Y, Z)

hsc1 =

2x1 graphics array: Surface Contour

colormap(turbo)

hsc1(2).LevelList = [min(Z(:)):0.5:-1 1:0.5:max(Z(:))];

hsc1(2).ZLocation = -10;

hold on

hsc2 = surfc(X, Y, Z)

hsc2 =

2x1 graphics array: Surface Contour

colormap(turbo)

hsc2(2).LevelList = [min(Z(:)):0.5:-1 1:0.5:max(Z(:))];

hsc2(2).ZLocation = 10;

hold off

view(-27,45)

This seems to be close to the plopt image you posted. The ZLocation property only accepts an integer argument, so using hold to draw the surface plot twice appears to be the only option oi more than one contour is desired.

.

Jialin Men 2024-7-25，20:36

Hallo Star,

That is so kind of you. It helps me really a lot. :)

Actually what I want is to see How f1 changes with x and y, or how it distributed with different x and y by contour plot, i thought the contour plot will be like the pictures i sent it you, however it is not.

Thanks so much again for your help. That is really important to me. If i have questions i may contact to you again.

Best regards

JL