Encodes logic of how to handle named-vector and functional palettes. Used primarily within embeddingGroupPlot()
fac2palette(groups, palette, unclassified.cell.color = "gray50")
vector or palette
vector of cluster labels, names contain cell names
vector or list or function (default=NULL). Accepts number of colors and return list of colors (i.e. see 'colorRampPalette')
Color for unclassified cells (default='gray50')