dplyr used to offer twin versions of each verb suffixed with an underscore. These versions had standard evaluation (SE) semantics: rather than taking arguments by code, like NSE verbs, they took arguments by value. Their purpose was to make it possible to program with dplyr. However, dplyr now uses tidy evaluation semantics. NSE verbs still capture their arguments, but you can now unquote parts of these arguments. This offers full programmability with NSE verbs. Thus, the underscored versions are now superfluous.

tally_(x, wt, sort = FALSE)

count_(x, vars, wt = NULL, sort = FALSE,
.drop = group_by_drop_default(x))

add_tally_(x, wt, sort = FALSE)

add_count_(x, vars, wt = NULL, sort = FALSE)

distinct_(.data, ..., .dots, .keep_all = FALSE)

do_(.data, ..., .dots = list())

funs_(dots, args = list(), env = base_env())

group_by_(.data, ..., .dots = list(), add = FALSE)

group_indices_(.data, ..., .dots = list())

filter_(.data, ..., .dots = list())

slice_(.data, ..., .dots = list())

summarise_(.data, ..., .dots = list())

summarize_(.data, ..., .dots = list())

mutate_(.data, ..., .dots = list())

transmute_(.data, ..., .dots = list())

arrange_(.data, ..., .dots = list())

select_(.data, ..., .dots = list())

rename_(.data, ..., .dots = list())

select_vars_(vars, args, include = chr(), exclude = chr())

rename_vars_(vars, args)

## Arguments

x a tbl() to tally/count. (Optional) If omitted (and no variable named n exists in the data), will count the number of rows. If specified, will perform a "weighted" tally by summing the (non-missing) values of variable wt. A column named n (but not nn or nnn) will be used as weighting variable by default in tally(), but not in count(). This argument is automatically quoted and later evaluated in the context of the data frame. It supports unquoting. See vignette("programming") for an introduction to these concepts. if TRUE will sort output in descending order of n Various meanings depending on the verb. see group_by() A data frame. If TRUE, keep all variables in .data. If a combination of ... is not distinct, this keeps the first row of values. Pair/values of expressions coercible to lazy objects. Various meanings depending on the verb. The environment in which functions should be evaluated. When add = FALSE, the default, group_by() will override existing groups. To add to the existing groups, use add = TRUE. Character vector of column names to always include/exclude.

## Details

Unquoting triggers immediate evaluation of its operand and inlines the result within the captured expression. This result can be a value or an expression to be evaluated later with the rest of the argument. See vignette("programming") for more information.