Plotting 3D for three independent variables without any function

I have four vectors as attached in Data_1.tx. file. I'm looking for a way to plot their surface map. Where X = (:,column3), Y = (:,column 2) and Z = (:,Column 1). I have looked into meshgrid but did not work since I do not have a function to estimate Z from given X and Y Values. They are only data. I have found and tried this below code but did not like the graph.

trisurf(delaunay(X,Y),X,Y,Z)

I have tried Scatter 3 as below and I do not like it. Is there anyway to present them as the below colourful box? Thank you for your help.

[Amanullah Khan]

Dear Mr.Walter Roberson,

I would like to plot the surface for 3 coulmns. I have plotted the points with the help of scatter3 commands. But I cannot plot the surface. Please could you tell me whichoption will be better for this data.

I would like to have something like this form the above raw data.

[Walter Roberson]

Please post the data as a readable file.

[Amanullah Khan]

Please find the attached data file

[Walter Roberson]

t = readtable('Surface plot.xlsx');
x = t.Temp; y= t.Pressure; z = t.Time;
tri = delaunay(x,y);
trimesh(tri, x, y, z);

[Amanullah Khan]

Thank you so much Mr Walter. It worked for me.

Answer 1

[Walter Roberson]

For a typical surface map, you would use

 interpolated_z = griddata(X, Y, Z, query_x, query_y);
 surf(query_x, query_y, interpolated_z, 'edgecolor', 'none')
 

However, the example diagram you give is an example of using https://www.mathworks.com/help/matlab/ref/slice.html on a 3D grid of data. You do not have the information necessary for that -- not unless the unused 4th column of your input is value information.

When I look at your data, it looks to me to be more likely that your first column is value information and that your remaining three columns are X, Y, Z coordinates, rather than your first column being Z coordinates.

[Yaser Khojah]

Thanks for your response. Is there anyway kindly you show how would you apply them on my data? I have tried them but did not get them. Feel free to use any values you like. I'm just trying to find any correlation between these vectors. Please note that I do not have any function to create the meshgrid. I only have the data and I do not know how to use meshgrid here.

If I want to use this

interpolated_z = griddata(X, Y, Z, query_x, query_y);

surf(query_x, query_y, interpolated_z, 'edgecolor', 'none')

What is the query_x and y?

[Walter Roberson]

[query_x, query_y] = meshgrid(linspace(min(X), max(X)), linspace(min(Y), max(Y));

[Yaser Khojah]

Dear Walter Thank you so much for this. One more thing please, how would you use slice here and I would go with the remaining three columns are X, Y, Z coordinates and column one as my v in. I'm not sure how I would calcualte the v value here since I do not have a function.

 slice(X,Y,Z,V,xslice,yslice,zslice)

I have tried this bud it did not work?

X = MaT_All(idx_Pos,17); % column 2
Y = MaT_All(idx_Pos,18); % column 3
Z = MaT_All(idx_Pos,19); % column 4
V = MaT_All(idx_Pos,16); % column 1

[X1,Y1,Z1] = meshgrid(0:5:60);
[query_x, query_y, query_z] = meshgrid(linspace(min(X), max(X)), linspace(min(Y), max(Y)), linspace(min(Z), max(Z))); 
interpolated_v              = griddata(X, Y, Z, V, query_x, query_y , query_z);
slice(X,Y,Z,V)

[Walter Roberson]

T = readtable('Data_1.txt');
V = T{:,1};
X = T{:,2};
Y = T{:,3};
Z = T{:,4};
[query_x, query_y, query_z] = meshgrid(linspace(min(X), max(X),50), linspace(min(Y), max(Y), 50), linspace(min(Z), max(Z), 50));
F = scatteredInterpolant(X, Y, Z, V);
interpV = F(query_x, query_y, query_z);
slice(query_x, query_y, query_z, interpV, [-50], [10], [10])

... but it will not look very useful.

I suggest that you use

volumeviewer(interpV)

and play around with the settings. Have a look at isosurface and MRI settings perhaps. It is not easy to get useful information out of it.

[Yaser Khojah]

Thank you so much, this is really useful. Is V presented by the colorbar?

[Walter Roberson]

Yes, V is represented as color.

You can also create a diagonal set of query points, and hold on and slice() with it. When I looked at the data I could not see any particular angle that it would make sense to slice at.

Answer 2

[M Naeem]

can you please help in plotting graph of f(x,y,z)=2x+5xy+11xyz+2z

[Walter Roberson]

N = 50;
xvec = linspace(-5,5,N);
yvec = linspace(-5,5,N);
zvec = linspace(-5,5,N);
[X,Y,Z] = meshgrid(xvec, yvec, zvec);
fxyz = 2 .* X + 5 .* X .* Y + 11 .* X .* Y .* Z + 2 .* Z;
minf = min(fxyz(:));
maxf = max(fxyz(:));
levels = linspace(minf, maxf, 9);
levels = levels(2:end-1);
nlev = length(levels);

for K = 1:nlev
   L = levels(K);
   isosurface(X, Y, Z, fxyz, L, fxyz);;
end

camlight; lighting phong

legend( string(levels) );
colorbar
hold off

[M Naeem]

Thank you soo much ...