How to combine three arrays containing x and y values and a magnitude, respectively, in order to produce contour plot?

Hi all,

I'm trying to create a filled contour plot in order to represent my data. However, functions like contourf require the input to be a matrix of values. I don't have a matrix of values, instead I have three arrays: one containing x-coordinates, one containing y-coordinates and a third array containing the magnitudes by which I want each coordinate point to be contoured. Is there any way to combine these three arrays into a matrix that can be read by a function such as contourf, or is there another function I can use which produces the same result but can read arrays instead? I've tried meshgrid and nfgrid but these just replicate the values in my arrays, which is not the result I want.

Thanks.

Answer 1

[Walter Roberson]

Nx = 129; Ny = 129;   %output graph should be Ny pixels high and Nx pixels wide
NL = 10;      %number of levels to use in output contour

xv = linspace(min(x), max(x), Nx);
yv = linspace(min(y), max(y), Ny);
[xq, yq] = ndgrid(xv, yv);
maggrid = griddata(x(:), y(:), magnitude(:), xq, yq);
contourf(xq, yq, maggrid, NL);

You can also replace NL with a vector of specific levels to draw contour lines at.

[Charis Horn]

Thank you! I think that worked.