Column in meta.data slot to group results by (default = "orig.ident").
default_var
logical. Whether to include the default meta.data variables of: "nCount_RNA",
"nFeature_RNA", "percent_mito", "percent_ribo", "percent_mito_ribo", and "log10GenesPerUMI"
in addition to variables supplied to median_var.
median_var
Column(s) in @meta.data to calculate medians for in addition to defaults.
Must be of class() integer or numeric.