What's the link between the size of XData and the original graphic?

I'm creating a graphic from a function that draws the Spectral Power Density of a signal, and going from there, I input the following code to extract the info.

ax = gca

h = findobj(gca, 'Type', 'line');

x= h.XData;

y = h.YData

The graph in question is this one:

And I'm trying to figure out why x and y have a size of 1025, when the graph has a length of over 2x10^4. I would like to know this so that, independently of the audio signal that I'm working with, I'll know with certainty what the size of x and y will be, so that I can get the peaks from there, since I can't assign the SPD to a variable if I'm supposed to use the function that I was given, because it has no outputs.

Thanks in advance.

Answer 1

[Jan]

The values of the line have a range until 22028.5, which is the "2x10^4". The number of values can be 1025.

This means, that the XData are the values of the x component.