Select lines on a surf plot and output indices

I have a plot (spectrogram) on which I added some lines. I would like to select some of these lines directly on the plot with the mouse and output the index of each selected line.

Here is part of my script for the plot

figure
hold on
H(1) = surf(t,f,20*log10(abs(s)),'EdgeColor', 'none');
axis xy;  axis tight; 
colormap(jet); view(0,90);
xlabel('Time (secs)');
colorbar;
ylabel('Frequency(Hz)'); 
% Add lines
ipt_sec = t(ipt); % Indices to seconds
 for i = 1:numel(ipt_sec)
     y = ylim;
     H(i)= plot([ipt_sec(i),ipt_sec(i)],[y(1) y(2)], 'LineWidth', 2, 'Color', 'k');
 end
 
set(H, 'ButtonDownFcn', {@LineSelected, H})

function LineSelected(ObjectH, EventData, H)
set(ObjectH, 'LineWidth', 4);
set(H(H ~= ObjectH), 'LineWidth', 2);
end

I would like to be able to select multiple lines (instead of just one in the script above) and output each of their index.

Any help greatly appreciated, thank you!

Answer 1

[KSSV]

Just use

surf(20*log10(abs(s)),'EdgeColor', 'k') 

Use getpts or ginput or daatip, this will give you location/ index where you have clicked on the plot. It has (i,j) r (row,column). Now you can use t(r,:) or t(:c) etc.

But why you want to click on the plot? You can use ==, <=, >= etc to get what you want.

[Butterflyfish]

Thanks! I want to manually select some of the line based on the colors of the spectrogram. Is there a way to specifically select such an object (xline) rather than a point on the plot?

[KSSV]

Select two points which lie on the same line.....you have the indices now.

Note that the colors are decided by the magnitude or value of the data. Still you can use logical comparisons.

[Butterflyfish]

Thanks, I have edited my question for more precisions. The function 'ButtonDownFcn' seems to work but I don't understand completely how it works, how to select multiple lines and output the indices.