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,
${\\displaystyle n_{1}=4\\pi \\int _{r_{0}}^{r_{1}}r^{2}g(r)\\rho \\,dr,}$
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