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#' Rename variables by name
#'
#' `step_rename` creates a *specification* of a recipe step that will add
#' variables using [dplyr::rename()].
#'
#' @inheritParams step_center
#' @param ... One or more unquoted expressions separated by commas. See
#' [dplyr::rename()] where the convention is **`new_name = old_name`**.
#' @param role For model terms created by this step, what analysis role should
#' they be assigned? By default, the function assumes that the new dimension
#' columns created by the original variables will be used as predictors in a
#' model.
#' @param inputs Quosure(s) of `...`.
#' @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 `values` which contains the `rename` expressions as character
#' strings (and are not reparsable).
#' @details When an object in the user's global environment is referenced in
#' the expression defining the new variable(s), it is a good idea to use
#' quasiquotation (e.g. `!!`) to embed the value of the object in the
#' expression (to be portable between sessions).
#' @keywords datagen
#' @concept preprocessing
#' @concept transformation_methods
#' @export
#' @examples
#' recipe( ~ ., data = iris) %>%
#' step_rename(Sepal_Width = Sepal.Width) %>%
#' prep() %>%
#' bake(new_data = NULL) %>%
#' slice(1:5)
#'
#' vars <- c(var1 = "cyl", var2 = "am")
#' car_rec <-
#' recipe(~ ., data = mtcars) %>%
#' step_rename(!!vars)
#'
#' car_rec %>%
#' prep() %>%
#' bake(new_data = NULL)
#'
#' car_rec %>%
#' tidy(number = 1)
step_rename <- function(
recipe, ...,
role = "predictor",
trained = FALSE,
inputs = NULL,
skip = FALSE,
id = rand_id("rename")
) {
inputs <- enquos(..., .named = TRUE)
add_step(
recipe,
step_rename_new(
terms = terms,
trained = trained,
role = role,
inputs = inputs,
skip = skip,
id = id
)
)
}
step_rename_new <-
function(terms, role, trained, inputs, skip, id) {
step(
subclass = "rename",
terms = terms,
role = role,
trained = trained,
inputs = inputs,
skip = skip,
id = id
)
}
#' @export
prep.step_rename <- function(x, training, info = NULL, ...) {
step_rename_new(
terms = x$terms,
trained = TRUE,
role = x$role,
inputs = x$inputs,
skip = x$skip,
id = x$id
)
}
#' @export
bake.step_rename <- function(object, new_data, ...) {
dplyr::rename(new_data, !!!object$inputs)
}
print.step_rename <-
function(x, width = max(20, options()$width - 35), ...) {
cat("Variable renaming for ",
paste0(names(x$inputs), collapse = ", "))
if (x$trained) {
cat(" [trained]\n")
} else {
cat("\n")
}
invisible(x)
}
#' @rdname step_rename
#' @param x A `step_rename` object
#' @export
tidy.step_rename <- function(x, ...) {
var_expr <- map(x$inputs, quo_get_expr)
var_expr <- map_chr(var_expr, quo_text, width = options()$width, nlines = 1)
tibble(
terms = names(x$inputs),
value = var_expr,
id = rep(x$id, length(x$inputs))
)
}
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