How do I recreate the wcoherence imagesc with the outputs wcoh, coi and f (without the arrows)?

I can't seem to get a comparable right yaxis and coi for my data. I am using-

[wcoh,wcs,f,coi]=wcoherence(data1,data2,fs);

t=0:1/fs:(length(data1)-1)/fs;

figure; imagesc(t./60./60,f,wcoh);

hold on; plot(t./60./60,coi,'--w','LineWidth',2);

set(gca,'YDir','normal');

My yaxis and coi (figure2) don't match what I get when using wcoherence (figure1) to plot.

Any help would be great! Thanks!

Answer 1

[Abhimenyu]

Hi Deepshikha,

I understand that you are using “wcoherence” function to compute the wavelet coherence and cross-spectrum of two signals, and then plotting the results using “imagesc” and “plot”.

To ensure that the y-axis and the cone of influence (COI) match in the plot, the y-axis limits must be set correctly using the “ylim” function as shown in the example code below:

Shape[wcoh,wcs,f,coi]=wcoherence(data1,data2,fs); 
t=0:1/fs:(length(data1)-1)/fs; 

% Plot the coherence 
figure; 

imagesc(t./60./60,f,wcoh); 
set(gca,'YDir','normal'); 
% Adjust the y-axis limits 
ylim([min(f) max(f)]); 

hold on;

% Plot the cone of influence (COI) 
plot(t./60./60,coi,'--w','LineWidth',2); 
% Adjust the y-axis limits for the COI 
ylim([min(f) max(coi)]); 

% Add labels and title 
xlabel('Time (hours)'); 
ylabel('Frequency'); 
title('Wavelet Coherence'); 

% Add colorbar 
colorbar; 

Please refer to the following documentation link below for more information on “ylim” function,

https://www.mathworks.com/help/releases/R2023a/matlab/ref/ylim.html

I hope this helps!

Thank you,

Abhimenyu.