l_setColorList_ggplot2.RdLoon's color list is used to map nominal values to colors. See
the documentation for l_setColorList.
l_setColorList_ggplot2()
l_setColorList, l_setColorList_loon,
l_setColorList_ColorBrewer, l_setColorList_hcl,
l_setColorList_baseR, l_setColorList_ggplot2