all.vars() and all.names(): Find All Names in an Expression Functions: all.names() and all.vars() Example: Code R : all.names(expression(sin(x+y))) all.names(quote(sin(x+y))) # or a call all.vars(expression(sin(x+y)))
droplevels The function droplevels() [in base package] is used to drop unused levels from a factor. Code R :droplevels(x) x: an object from which to drop unused factor levels
