Example of the graphical output of the code. Top panel: postage stamp of the close pair in the I band. The red cross marks the principal galaxy, the blue cross the companion galaxy. The red circle marks at z_min = 0.4. The text at the right summarises the main properties of the pair. Middle left panel: PDFs of the principal and companion galaxy and the function of the system (Sect. 3.2.2, Fig. 5). Middle right panel: angular mask ℳ^θ of the system (Sect. 3.2.3, Fig. 6). Bottom panels: pair selection mask of the system. Left panel: selection of the primary and secondary sample (Sect. 3.2.4, Fig. 7), right panel: luminosity ratio constraint of the system (Sect. 3.2.4, Fig. 8). (Colour version online.)