It is often flexible to input variables in plotting functions, and this
generic function convert most common inputs (character, numeric or formula)
to a character vector of variable names.
Usage
var_names(vars, data)
"var_names"(vars, data)
"var_names"(vars, data)
"var_names"(vars, data)
"var_names"(vars, data)
Arguments
vars
a character vector of variable names, or a numeric vector of
column indices, or a two-sided formula like ~ x1 + x2 + x3
data
the data containing the variables
Value
A character vector
Details
Numeric indices are converted to character names according to the positions
of variables in the data; all.vars is used to extract all
variable names in a formula, and the special formula ~ . is treated
differently: it means all variables in the data except thoese names starting
with a dot (e.g. .color).