Surf plot for three independent matrices of 1x360

Hey , I have three matrices of equal dimensions and i want to make a surf plot for it. Can someone help me with it. Basically X,Y are coordinates of the position and Z is the value at that Point. Thanks in advance for everyone who tries to help.

Answer 1

[Star Strider]

You have one matrix of three (1x360) row vectors. If your data are gridded, simply use the reshape function on each row vector to create appropriate matrices from them.

If your data are not gridded (random), use the griddata function (or similar functions) to create appropriate matrices for the surf plot.

One easy way to see if your data are gridded is to plkot them using the stem3 function. If they are gridded, that will be obvious.

[Anisha Varughese]

Hey,

They are three different matrices, each of 1x360 . So that part is ok. How do I plot using surf since z is not a function of x and y

[Star Strider]

See the documentation for the griddata function, that I linked to in my Answer.

[Anisha Varughese]

How do i get V?

[Star Strider]

If you’re referring to:

vq = griddata(x,y,v,xq,yq)

the ‘v’ vector is your dependent variable.

See the section: Interpolate Scattered Data Over Uniform Grid.

[Anisha Varughese]

Thanks I will check that out

[Star Strider]

My pleasure.

[Anisha Varughese]

Hey ,

Thats the thing I don't have a dependant vector. Do you have any idea how to make a surface plot of three independant values

[Star Strider]

Please attach your vectors, and a description of what they represent. I cannot go further without that information. It may be that a volume — not a surface — representation is most appropriate.

[Anisha Varughese]

X and Y are coordinates and Z is velocity at that position. The files are too big to attach. sorry.

[Star Strider]

‘X and Y are coordinates and Z is velocity at that position.’

That means that your two independent variable vectors are ‘X’ and ‘Y’, and your dependent variable vector is ‘Z’. My original Answer using griddata should work with your vectors.

A (3x360) matrix should not be too large to attach here.

Try this with your data:

X = rand(1, 360);                                   % Create Vector
Y = rand(1, 360);                                   % Create Vector
Z = rand(1, 360);                                   % Create Vector

N = 50;                                             % Grid Matrix Size
xv = linspace(min(X), max(X), N);                   % ‘X’ Vector To Define Interpolation Matrix
yv = linspace(min(Y), max(Y), N);                   % ‘Y’ Vector To Define Interpolation Matrix

[Xm,Ym] = meshgrid(xv, yv);                         % Create Interpolation Matrices

Zm = griddata(X, Y, Z, Xm, Ym);                     % Interpolate Vectors To Grids

figure
surfc(Xm, Ym, Zm)
grid on
xlabel('X')
ylabel('Y')
zlabel('Z')

That should work with your vectors without further modification. Much depends on the vectors themselves, of course, and I do not have them to work with.