Matlab contour plot with color

Can anyone tell how to plot the contour like this (shown in fig) in MATLAB

Answer 1

[Cris LaPierre]

Use contourf.

Answer 2

[Star Strider]

Use the contourf function, and choose the colormap that most closely represents what you want (for shades-of-gray, the gray colormap would lilkely be best).

[mukesh bisht]

I have the following condition: matrix X: x coordinates, matrix Y : y coordinates, matrix Z : velocity corresponding to each (x,y).

While using contourf function it shows following error "Z must be at least a 2x2 matrix."

[Star Strider]

It appears that all three of them are vectors, or that error would not appear.

One possibility is that the vectors represent gridded data, so simply using the reshape function with each of them (with the same reshape parameters for each vector) would work. To use it, it would be necessary to know at least one dimension of the matrix (rows or columns). There are several ways to do that, one is using the unique function on either ‘x’ or ‘y’ and determining the number of unique values by the number of elements in the first output.

Alternatively, try something like this —

N = 50;
xv = linspace(min(x), max(x), N);
yv = linspace(min(y), max(y), N);
[X,Y] = ndgrid(xv, yv);
Z = griddata(x, y, z, X, Y);

figure
contourf(X, Y, Z)
colormap('gray')

Change ‘N’ (or use different values for each linspace call), depending on the result you want.