plot3

how do a plot3 of a wavelet tranform showing time, scale and wavelet coefficients

Answer 1

[Wayne King]

Hi Lisa, To use plot3, you must have your time (position) and scale vectors as matrices because the CWT coefficients are in a matrix.

You can use meshgrid() to transform your time and scale vectors into matrices suitable for plot3()

t = 1:1024;
a = 1:30;
Wt = abs(randn(30,1024));
[T,A] = meshgrid(t,a);
plot3(T,A,Wt); xlabel('time'); 
ylabel('Scale'); zlabel('CWT magnitude');

However, I think you may find surf() better here

    surf(t,a,Wt); shading interp;
    xlabel('time'); ylabel('scale'); zlabel('CWT magnitude');

[Lisa Justin]

thanks! i will try it now

Answer 2

[Honglei Chen]

Hi Lisa,

I don't think plot3 is appropriate for your purpose. I think you probably better off using image or imagesc.

HTH

Answer 3

[Wayne King]

Hi Lisa, If I remember correctly you are using your own CWT algorithm, not MATLAB's cwt() or cwtft(). Is that correct? Are you coefficients in a matrix scale-position? I think you want surf

load vonkoch
vonkoch=vonkoch(1:510); 
len = length(vonkoch);
cw1 = cwt(vonkoch,1:32,'sym2','plot'); 
% cw1 is 32x510
surf(1:510,1:32,cw1); shading interp;
xlabel('Position'); ylabel('Scale'); zlabel('CWT Coefficients');
colormap jet;
view([-27 42]);

Keep in mind that if you are using a complex-valued analyzing wavelet, you will have to input the moduli (abs()), or the real or imaginary parts.