R: Get variable (names) from various R objects

get.vars {formula.tools} | R Documentation

## Get variable (names) from various R objects

### Description

`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.

### Usage

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

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

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

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

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

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

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

    lhs.vars(x, ...)

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

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

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

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

    rhs.vars(x, ...)

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

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

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

    ## S4 method for signature '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 )
      get.vars( quote( Sepal.Length * Sepal.Width ), iris )

[Package formula.tools version 1.7.1 Index]