How to get density to calculate coordination number from RDF

JB 2016-10-24

Dear All,
I want to calculate coordination number from RDF, I'm using the following equation,
$n_{1}=4\pi \int _{r_{0}}^{r_{1}}r^{2}g(r)\rho \,dr,$
However, I'm confused about the density, is this the density of atom i within the sphere volume of V(r1)? How can we get it?

Thank you!

Regards,
Jingjing