Contourf plot of datasets

Does anyone know how can I have a 2D-contour plot of some given data points?

I have the coordinates inside two vectors x and y. The problem is there is no analyctical function relating the height z, to the coordinates.

I have a seperate vector which has the values of z corrospondig to each (x,y) pair.

I would appreciate if you could help me with this.

Thanks in advance!

Answer 1

[Star Strider]

You might find the griddata function useful. It takes random (x,y) values and interpolates gridded z-matrices from them that contour and contourf can use.

[Parham Ebrahimi]

Thanks for your response.

The problem is still that I do not know how the relate the Z vector to the X and Y. Check out the following example:

x=1:8;
y=x;
[X,Y]=meshgrid(x,y)
Z=sin(X)+cos(Y)%This is an example of analyctical function for Z.
%However, I miss this function. Since I only have a vector for Z with stored data

[Star Strider]

My pleasure.

You do not need a function to create ‘Z’, since in your situation ‘Z’ are data you collect. You can create a contour plot of ‘Z’ when you have it as a matrix. If your data are already gridded, you only have to use the reshape function to create matrices from your vectors. Otherwise, you need to use the griddata function to create the ‘Z’ matrix.

If you want to fit a function to your data, that is possible. However, you first need a function that you are reasonably certain describes your data.

[Parham Ebrahimi]

You were right. I tried with reshape and it worked. Now I will interpolate to generate more data in the contour.

Thanks!

[Star Strider]

As always, my pleasure!