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#' Convert Factors to Strings
#'
#' `step_factor2string` will convert one or more factor
#' vectors to strings.
#'
#' @inheritParams step_center
#' @inherit step_center return
#' @param ... One or more selector functions to choose which
#' variables will be converted to strings. See [selections()]
#' for more details. For the `tidy` method, these are not
#' currently used.
#' @param role Not used by this step since no new variables are
#' created.
#' @param columns A character string of variables that will be
#' converted. This is `NULL` until computed by
#' [prep.recipe()].
#' @return An updated version of `recipe` with the new step
#' added to the sequence of existing steps (if any). For the
#' `tidy` method, a tibble with columns `terms` (the
#' columns that will be affected).
#' @keywords datagen
#' @concept preprocessing
#' @concept variable_encodings
#' @concept factors
#' @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.
#' @seealso [step_string2factor()] [step_dummy()]
#' @examples
#' library(modeldata)
#' data(okc)
#'
#' rec <- recipe(~ diet + location, data = okc)
#'
#' rec <- rec %>%
#' step_string2factor(diet)
#'
#' factor_test <- rec %>%
#' prep(training = okc,
#' strings_as_factors = FALSE) %>%
#' juice
#' # diet is a
#' class(factor_test$diet)
#'
#' rec <- rec %>%
#' step_factor2string(diet)
#'
#' string_test <- rec %>%
#' prep(training = okc,
#' strings_as_factors = FALSE) %>%
#' juice
#' # diet is a
#' class(string_test$diet)
#'
#' tidy(rec, number = 1)
step_factor2string <-
function(recipe,
...,
role = NA,
trained = FALSE,
columns = FALSE,
skip = FALSE,
id = rand_id("factor2string")) {
add_step(
recipe,
step_factor2string_new(
terms = ellipse_check(...),
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 <- eval_select_recipes(x$terms, training, info)
fac_check <-
vapply(training[, col_names], is.factor, logical(1))
if (any(!fac_check))
rlang::abort(
paste0(
"The following variables are not factor vectors: ",
paste0("`", names(fac_check)[!fac_check], "`", collapse = ", ")
)
)
step_factor2string_new(
terms = x$terms,
role = x$role,
trained = TRUE,
columns = col_names,
skip = x$skip,
id = x$id
)
}
#' @export
bake.step_factor2string <- function(object, new_data, ...) {
new_data[, object$columns] <-
map_df(new_data[, object$columns],
as.character)
if (!is_tibble(new_data))
new_data <- as_tibble(new_data)
new_data
}
print.step_factor2string <-
function(x, width = max(20, options()$width - 30), ...) {
cat("Character variables from ")
printer(x$columns, x$terms, x$trained, width = width)
invisible(x)
}
#' @rdname step_factor2string
#' @param x A `step_factor2string` object.
#' @export
tidy.step_factor2string <- function(x, ...) {
res <- simple_terms(x, ...)
res$id <- x$id
res
}
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