A computer algorithm for grouping a derived spatial arrangement of wireless communication nodes. The wireless communication nodes form a wireless communication network and are configured to control the operation of luminaires in a lighting array. The position of each node in the communication network corresponds to the position of a particular luminaire in the lighting array. The algorithm divides the arrangement of nodes into a plurality of spatial groups, each of which is defined by a line which joins the group's member nodes together. The groups are ranked according to their statistical attributes and a number of groups are selected as control groups, such that the member nodes, and hence luminaires, of each control group may be controlled by a single switch or sensor.