Get or set formula components

f_rhs extracts the right-hand side, f_lhs extracts the left-hand side, and f_env extracts the environment in which the formula was defined. All functions throw an error if f is not a formula.

Usage

f_rhs(f)

f_rhs(x) <- value

f_lhs(f)

f_lhs(x) <- value

f_env(f)

f_env(x) <- value

Arguments

f, x

A formula

value

The value to replace with.

Value

f_rhs and f_lhs return language objects (i.e. atomic vectors of length 1, a name, or a call). f_env returns an environment.

Examples

f_rhs(~ 1 + 2 + 3)
#> 1 + 2 + 3
f_rhs(~ x)
#> x
f_rhs(~ "A")
#> [1] "A"
f_rhs(1 ~ 2)
#> [1] 2

f_lhs(~ y)
#> NULL
f_lhs(x ~ y)
#> x

f_env(~ x)
#> <environment: 0x557a345fdf38>
f <- as.formula("y ~ x", env = new.env())
f_env(f)
#> <environment: 0x557a3440a880>