Functions for GGE (genotype plus genotype-by-environment) and GGB (genotype plus genotype-by-block-of-environments) biplots.
In the example GGE biplot below, the genotypes are shown by green labels and the environments are shown by blue/gold labels. Each color determines a mega-environment or block-of-environments. A thick, solid line is drawn from the origin to the ‘average’ of the environments within each block, and then a thinner line is drawn from the average to the individual environments. These ‘residual’ vectors show the deviations within each group. A dashed line extends to the edge of the plotting window and labels the group.