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#' Convert Factors to Strings
#'
#' `step_factor2string` will convert one or more factor vectors to strings.
#'
#' @inheritParams step_center
#' @param columns A character string of variables that will be converted. This
#' is `NULL` until computed by [prep()].
#' @template step-return
#' @family dummy variable and encoding steps
#' @export
#' @details `prep` has an option `strings_as_factors` that defaults to `TRUE`.
#' If this step is used with the default option, the string(s() produced by
#' this step will be converted to factors after all of the steps have been
#' prepped.
#'
#' # Tidying
#'
#' When you [`tidy()`][tidy.recipe()] this step, a tibble with columns `terms`
#' (the columns that will be affected) is returned.
#'
#' @template case-weights-not-supported
#'
#' @examplesIf rlang::is_installed("modeldata")
#' data(Sacramento, package = "modeldata")
#'
#' rec <- recipe(~ city + zip, data = Sacramento)
#'
#' make_string <- rec %>%
#' step_factor2string(city)
#'
#' make_string <- prep(make_string,
#' training = Sacramento,
#' strings_as_factors = FALSE
#' )
#'
#' make_string
#'
#' # note that `city` is a string in recipe output
#' bake(make_string, new_data = NULL) %>% head()
#'
#' # ...but remains a factor in the original data
#' Sacramento %>% head()
step_factor2string <-
function(recipe,
...,
role = NA,
trained = FALSE,
columns = FALSE,
skip = FALSE,
id = rand_id("factor2string")) {
add_step(
recipe,
step_factor2string_new(
terms = enquos(...),
role = role,
trained = trained,
columns = columns,
skip = skip,
id = id
)
)
}
step_factor2string_new <-
function(terms, role, trained, columns, skip, id) {
step(
subclass = "factor2string",
terms = terms,
role = role,
trained = trained,
columns = columns,
skip = skip,
id = id
)
}
#' @export
prep.step_factor2string <- function(x, training, info = NULL, ...) {
col_names <- recipes_eval_select(x$terms, training, info)
check_type(training[, col_names], types = c("factor", "ordered"))
step_factor2string_new(
terms = x$terms,
role = x$role,
trained = TRUE,
columns = col_names,
skip = x$skip,
id = x$id
)
}
#' @export
bake.step_factor2string <- function(object, new_data, ...) {
check_new_data(names(object$columns), object, new_data)
new_data[, object$columns] <- map(new_data[, object$columns], as.character)
new_data
}
print.step_factor2string <-
function(x, width = max(20, options()$width - 30), ...) {
title <- "Character variables from "
print_step(x$columns, x$terms, x$trained, title, width)
invisible(x)
}
#' @rdname tidy.recipe
#' @export
tidy.step_factor2string <- function(x, ...) {
res <- simple_terms(x, ...)
res$id <- x$id
res
}
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