Contour Plots from column vector

Hi,

I am trying to obtain a filled contour plot from three column vectors. The first vector is the x-coordinate, the second vector is the y-coordinate and the third vector is the temperature at corresponding x,y location. The three column vector data have been exported from a simulation result. I have attached the text file here.

Image 1 shows the scatter plot of the x-y coordinates.

I tried the following piece of code and the resulting contour plot looks something like this (Image 2).

[xq,yq] = meshgrid(x,y);            % x = first column, y = second column
[X1,Y1,Z1] = griddata(x,y,z,xq,yq); % z = third column
contourf(X1,Y1,Z1,200,'LineStyle','none')

I used the contour plot from a third party software and the correct resulting plot is image 3. I am trying the get the same result using Matlab.

Can someone please help me with this?

Thank you!

Answer 1

[Star Strider]

Try this —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/827635/Temperature%20data.txt', 'VariableNamingRule','preserve')

T1 = 1873×3 table
      Var1          Var2        Var3 
    _________    __________    ______

    0.0099362    0.00044647    2.2511
    0.0099362    0.00056765    2.1114
    0.0098083    0.00044647    2.1227
    0.0098083    0.00056765    2.0295
    0.0096809    0.00044647    2.0236
    0.0096809    0.00056765    1.9602
    0.0095536    0.00044647    1.9418
    0.0095536    0.00056765    1.8966
    0.0094258    0.00044647    1.8734
    0.0094258    0.00056765    1.8412
    0.0092983    0.00044647    1.8159
    0.0092983    0.00056765    1.7929
    0.0091582    0.00044647    1.7629
    0.0091582    0.00056765    1.7472
    0.0090055    0.00044647    1.7149
    0.0090055    0.00056765    1.7049

xv = linspace(min(T1.Var1), max(T1.Var1), numel(T1.Var1));
yv = linspace(min(T1.Var2), max(T1.Var2), numel(T1.Var2));

[Xm,Ym] = ndgrid(xv, yv);
Zm = griddata(T1.Var1, T1.Var2, T1.Var3, Xm, Ym);

figure
contourf(Xm, Ym, Zm, 15, 'ShowText','on')

figure
surfc(Xm, Ym, Zm, 'EdgeColor','none')
grid on
view(150,30)

.