poincare plot of heart sound

I have following data: Sample frequency=11025; numbers of bits=16; y(file size)=<47326x1 double>.

I need to make RRI[i](sec) vs RRI[i+1](sec) poincare plot, where RRI is R-R interval. How do it?

Answer 1

[Dishant Arora]

X = RRI;
X(end)=[];
Y=RRI;
Y(1)=[];
plot(Y,X,'.');

Answer 2

[Saifuddin Chowdhury]

how to calculate RR interval in second for given data?

I want to do it by autocorreltion.

   x=xcorr(y);

[Dishant Arora]

time between two successive RR samples will be simply 1/Fs.