This helper is intended to provide equivalent semantics to
select(). It is used for instance in scoped summarising and
mutating verbs (mutate_at() and summarise_at()).
vars(...)Variables to include/exclude in mutate/summarise. You
can use same specifications as in select(). If missing,
defaults to all non-grouping variables.
These arguments are automatically quoted and later
evaluated in the context of the data
frame. They support unquoting. See
vignette("programming") for an introduction to these concepts.
Note that verbs accepting a vars() specification also accept an
integerish vector of positions or a
character vector of column names.
funs(), all_vars() and any_vars() for other quoting
functions that you can use with scoped verbs.