Retrieve N number of discrete samples from a continuous audio sample

I'm attempting to extract N number of linearly spaced samples of data (i.e. the x and y coordinates) from a continuous graph I made using the audioread function. Here is my code as follows:

[N,fs] = audioread('Piano Middle C.wav');
t=linspace(0,length(N)/fs,length(N));
plot(t,N)

[Geoff Hayes]

Abbass - what exactly is your question? There are N samples in your wav file so what do you want to retrieve?