Get variable (names) from various R objects

get.vars extracts variable names from various R objects such as formulas, expressions, calls, symbols, etc. It is very similar to all.vars except that all symbols, etc. are interpolated to the names of variables.

get.vars(x, data = NULL, ...)

# S4 method for class 'formula,ANY'
get.vars(x, data = NULL, ...)

# S4 method for class 'call,ANY'
get.vars(x, data = NULL, ...)

# S4 method for class 'expression,missing'
get.vars(x, data = NULL, ...)

# S4 method for class 'name,ANY'
get.vars(x, data = NULL, ...)

# S4 method for class 'ANY,ANY'
get.vars(x, data = NULL, ...)

# S4 method for class '`NULL`,ANY'
get.vars(x, data = NULL, ...)

lhs.vars(x, ...)

.lhs.vars(x, ..., data = NULL)

# S4 method for class 'formula'
lhs.vars(x, ..., data = NULL)

# S4 method for class 'call'
lhs.vars(x, ..., data = NULL)

# S4 method for class 'expression'
lhs.vars(x, ...)

rhs.vars(x, ...)

.rhs.vars(x, ..., data = NULL)

# S4 method for class 'formula'
rhs.vars(x, ..., data = NULL)

# S4 method for class 'call'
rhs.vars(x, ..., data = NULL)

# S4 method for class 'expression'
rhs.vars(x, ...)

Arguments

x

object to extract vars from.

data

data set/list or environment on which the names are defined

...

arguments passed to subsequent functions

get.vars and variant get the variables from objects optionally interpreting on . on the data. This is useful, for example, when you wish to know what data is used based on a given formula.

Methods/functions beginning with . are not exported

Value

character vector of variables names in order that they appear in x.

See also

all.vars

Examples

  get.vars( Species ~ ., iris )
#> [1] "Species"      "Sepal.Length" "Sepal.Width"  "Petal.Length" "Petal.Width" 
  get.vars( quote( Sepal.Length * Sepal.Width ), iris )
#> [1] "Sepal.Length" "Sepal.Width"