Early-type galaxies (the black dots) and the galaxies used for the environment measurement (the gray dots) in the redshift-absolute r-band magnitude space. The stellar mass is also indicated on the y-axis on the right, assuming the light–mass relation (Equation (3)) of early-type galaxies. So, the stellar mass values are only applicable for early-type galaxies. The redshifts of the early-type galaxies are spectroscopic redshifts, while those of the galaxies used for the environment measurement are photometric redshifts. Only 150,000 galaxies used for the environment measurement are shown here for display. The green vertical dashed lines indicate the redshift cut for the early-type galaxies. The red lines represent the boundary for the volume-limited sample of the galaxies used for the environment measurement.