Representative average spectra obtained by grouping the VIPERS spectra through a group-finding algorithm into 15 classes in the (θ, ϕ) plane, as labelled in Fig. 13. We average the repaired and cleaned spectra (i.e. considering only the three principal components). In the top frame, we show that spectra 1–8 follow a sequence from early to late types, with the continuum becoming progressively bluer and with stronger [O ii] emission. Note that the spectrum labelled as 1, i.e. the reddest one, still presents a hint of emission lines (although pure red spectra exist in the sample), since it is an average spectrum. In the bottom frame, spectra 9–13 represent starburst galaxies with flatter continua and strong emission lines. The mean spectra 14 and 15 effectively seem to pertain to none of the two branches, showing a mixture of blue and red galaxy properties.