#' Functions for working with the vctrs package
#'
#' These make it clear that we need to use the tibble behavior when joining,
#' concatenating or casting `skim_df` objects. For a better discussion, on
#' why this is important and how these functions work, see:
#' <https://vctrs.r-lib.org/reference/howto-faq-coercion-data-frame.html>.
#'
#' `vec_ptype2.*` handles finding common prototypes between `skim_df` and
#' similar objects. `vec_cast.*` handles casting between objects. Note that
#' as of `dplyr 1.0.2`, [dplyr::bind_rows()] does not full support combining
#' attributes and [vctrs::vec_rbind()] is preferred instead.
#'
#' @importFrom vctrs vec_ptype2 vec_cast
#' @name skimr-vctrs
#' @keywords internal
NULL
#' @rdname skimr-vctrs
#' @export
vec_ptype2.skim_df.skim_df <- function(x, y, ...) {
combine_compatible_objects(x, y, ...)
}
#' @rdname skimr-vctrs
#' @export
vec_ptype2.skim_df.tbl_df <- function(x, y, ...) {
combine_compatible_objects(x, y, ...)
}
#' @rdname skimr-vctrs
#' @export
vec_ptype2.tbl_df.skim_df <- function(x, y, ...) {
combine_compatible_objects(x, y, ...)
}
#' @rdname skimr-vctrs
#' @export
vec_cast.skim_df.skim_df <- function(x, to, ...) {
cast_compatible_object(x, to, ...)
}
#' @rdname skimr-vctrs
#' @export
vec_cast.skim_df.tbl_df <- function(x, to, ...) {
vctrs::tib_cast(x, to, ...)
}
#' @rdname skimr-vctrs
#' @export
vec_cast.tbl_df.skim_df <- function(x, to, ...) {
vctrs::tib_cast(x, to, ...)
}
#' We only combine skim_df's that were built with the same set of skimmers.
#' @noRd
has_compatible_skimmers <- function(x, y) {
has_identical_base(x, y) && has_identical_skimmers(x, y)
}
has_identical_base <- function(x, y) {
base_x <- attr(x, "base_skimmers") %||% attr(y, "base_skimmers")
base_y <- attr(y, "base_skimmers") %||% attr(x, "base_skimmers")
identical(base_x, base_y)
}
has_identical_skimmers <- function(x, y) {
skim_list_x <- attr(x, "skimmers_used") %||% attr(y, "skimmers_used")
skim_list_y <- attr(y, "skimmers_used") %||% attr(x, "skimmers_used")
x_names <- names(skim_list_x)
y_names <- names(skim_list_y)
all_names <- union(x_names, y_names)
all(purrr::map_lgl(
all_names,
check_identical_skimmers,
x_names,
y_names,
skim_list_x,
skim_list_y
))
}
check_identical_skimmers <- function(name,
x_names,
y_names,
skim_list_x,
skim_list_y) {
if ((name %in% x_names) && (name %in% y_names)) {
identical(skim_list_x[name], skim_list_y[name])
} else {
TRUE
}
}
combine_compatible_objects <- function(x, y, ..., x_arg = "", y_arg = "") {
if (!has_compatible_skimmers(x, y)) {
vctrs::stop_incompatible_type(
x,
y,
x_arg = x_arg,
y_arg = y_arg,
details = "Can't combine different sets of skim functions."
)
}
if (could_be_skim_df(x) && could_be_skim_df(y)) {
reassign_skim_attrs(
vctrs::tib_ptype2(x, y, ...),
x,
data_rows = data_rows(x) + data_rows(y),
data_cols = data_cols(x) + data_cols(y),
df_name = paste0(df_name(x), "+", df_name(y)),
groups = c(group_names(x), group_names(y)),
skimmers_used = union(skimmers_used(x), skimmers_used(y))
)
} else {
strip_skim_attrs(vctrs::tib_ptype2(x, y, ...))
}
}
cast_compatible_object <- function(x, to, ..., x_arg = "", to_arg = "") {
out <- vctrs::tib_cast(x, to, ..., x_arg = x_arg, to_arg = to_arg)
if (could_be_skim_df(out)) {
reassign_skim_attrs(out, to)
} else {
strip_skim_attrs(out)
}
}
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