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Create A Formula

create_form.Rd

A convenient utility to quickly generate formula objects in a standardized format and environment.

Usage

create_form(response, features, collapse = c("+", "*"), env = NULL)

Arguments

response

A quoted string representing the LHS of the formula, i.e. the response variable (Y).

features

A vector of quoted strings representing the model features/predictors. Used to generate the right-hand side (RHS) of the formula.

collapse

character(1). The separator for features. Typically either + for main effects, * for interactions.

env

The environment in which to evaluate the formula. To keep the formula object as light-weight as possible, the default is the current function environment/scope. However, some occasions (e.g. unit testing) may require the formula's environment to capture certain objects necessary to fit a model (e.g. weights).

Value

A stats formula. See formula().

See also

eval(), environment()

Author

Stu Field

Examples

ft <- c("ft_1234.56", "ft_8899.8", "ft_3334.3")
f1 <- create_form("class", ft)
print(f1, showEnv = FALSE)
#> class ~ ft_1234.56 + ft_8899.8 + ft_3334.3

# environment manipulation
# cleanest light-weight formula (default)
ls(environment(f1))
#> [1] "env"  "expr"

# capture another environment
e     <- new.env()
e$new <- LETTERS
e$obj <- rnorm(100)
f2    <- create_form("class", ft, env = e)
ls(environment(f2))
#> [1] "new" "obj"