MATLAB: Contourf plot of datasets

2d contourcontourcontourfdatasets

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!

Best Answer

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.

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MATLAB: Putting function values in meshgrid format

Your data may already be gridded. I would first plot it using stem3, for example:

figure
stem3(X, Y, Z)
grid on

If it appears that the data are regularly spaced with respect to ‘X’ and ‘Y’, then you only need to use reshape to create matrices from your vectors. If you then want to interpolate it, the griddata function may be easiest to use.

MATLAB: Contour from .xlsx, getting “Z must be at least a 2×2 matrix” error

You first need to convert you z vector into a grid to use contour()

data = xlsread('data.xlsx','Sheet1','A1:C300');
x = data(:,2);
y = data(:,1);
z = data(:,3);
xg = linspace(min(x), max(x), 50);
yg = linspace(min(y), max(y), 50);
[X,Y]=meshgrid(xg,yg);
Z = griddata(x, y, z, X, Y);
contour(X,Y,Z)

Best Answer

Related Solutions

MATLAB: Putting function values in meshgrid format

MATLAB: Contour from .xlsx, getting “Z must be at least a 2×2 matrix” error

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