MATLAB: Modifying contour levels from GUI

contourMATLAB

How can I change contour levels from the contour plot GUI?

Best Answer

There may not be a straightforward to do what is being asked for. But, while the contour plot is active, if the 'contour' command is executed with same arguments and an additional argument specifying the number of contour levels the same plot gets updated to reflect the specified number of contours.

The following code (taken from the documentation of ' contour ' command) illustrates this:

x = -2:0.2:2;
y = -2:0.2:3;
[X,Y] = meshgrid(x,y);
Z = X.*exp(-X.^2-Y.^2);
figure
contour(X,Y,Z)

Now if we try:

contour(X,Y,Z,8) 
% Plot gets updated to show 8 contours

Using GUIDE or App Designer, one can have an interface in the GUI to change the number of levels and use the above mentioned command in the callback to do what is being asked for.

Hope this helps!

Related Solutions

MATLAB: How to get coordinates for a specific contour line

x = -2:0.2:2;
y = -2:0.2:3;
[X,Y] = meshgrid(x,y);
hold on % to your meshgrid a specific value for your contour.
[x1,y1] = contour(X,Y,Z,[0.1 0.1],'*k') % x1 will be your "two-column matrix"

MATLAB: How to label the levels of a fcontour plot

You must use the contour function to get the contour labels.

Combining fcontour and contour to get the result you want (in figure(2) here) is not difficult. You first need to get the data fcontour creates. You can do that by returning the handle to it, and then accessing its properties.

Using an example from the documentation for fcontour and adapting it to use contour:

syms f(x,y)
f(x,y) = sin(x) + cos(y);
figure(1)
hfc = fcontour(f);
figure(2)
contour(hfc.XData, hfc.YData, hfc.ZData, 'ShowText','on')

Although this takes one more line of code, it will give you the result you want.

Best Answer

Related Solutions

MATLAB: How to get coordinates for a specific contour line

MATLAB: How to label the levels of a fcontour plot

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