Figure 9

Calculating PCFs. Schematic diagram to illustrate the method used to calculate PCFs. For each distance interval (r _k , r _{k +1}] and each cell with centre x _m , we count the number of (other) cells in r _k <r ≤ r _{k +1} where r is distance from x _m . The PCF, g(r), on r _k <r ≤ r _{k+ 1} is the mean number of cells in these annular regions normalised by $\pi \left(r_{k+1}^2-r_k^2\right)\rho$, which is the number of other cells which would be expected to be found in the annular region were the cells uniformly distributed (see equations (10)-(11)). For the cross PCFs g _XY (r), we restrict x _m to be of type X and only count cells of type Y; g _S (r) is calculated from g _RR (r) and g _GG (r) by (12).