paleolimbot commented on code in PR #35543:
URL: https://github.com/apache/arrow/pull/35543#discussion_r1237227776
##########
r/R/dplyr-collect.R:
##########
@@ -192,5 +192,6 @@ implicit_schema <- function(.data) {
aggregate_types(.data, hash, old_schm)
)
}
- schema(!!!new_fields)
+
+ schema(new_fields)
Review Comment:
If you feel strongly about the ability to pass a bare list instead of
`!!!bare_list` I think this is a better fit for a separate PR: it is not
related to the ability to use `schema()` on a
Dataset/ArrowTabular/arrow_dplyr_query and is a departure from behaviour
elsewhere in the package (e.g., none of `record_batch()`, `arrow_table()`, or
`struct()` support this).
##########
r/R/schema.R:
##########
@@ -244,10 +230,59 @@ print_schema_fields <- function(s) {
paste(map_chr(s$fields, ~ .$ToString()), collapse = "\n")
}
-#' @param ... [fields][field] or field name/[data type][data-type] pairs
+#' Schemas
+#'
+#' Create a schema or extract one from an object.
+#'
+#' @seealso [Schema] for detailed documentation of the Schema R6 object
+#' @param ... [fields][field], field name/[data type][data-type] pairs, or
object from which to extract a schema
+#' @examples
+#' # Create schema using pairs of field names and data types
+#' schema(a = int32(), b = float64())
+#'
+#' # Create schema using fields
+#' schema(
+#' field("b", double()),
+#' field("c", bool(), nullable = FALSE),
+#' field("d", string())
+#' )
+#'
+#' # Extract schemas from objects
+#' df <- data.frame(col1 = 2:4, col2 = c(0.1, 0.3, 0.5))
+#' tab1 <- arrow_table(df)
+#' schema(tab1)
+#' tab2 <- arrow_table(df, schema = schema(col1 = int8(), col2 = float32()))
+#' schema(tab2)
+#' @export
+schema <- function(...) {
+ dots <- list2(...)
+
+ if (length(dots) == 1 && !is.list(dots[[1]]) && is.null(names(dots)) &&
!inherits(dots[[1]], "Field")) {
+ return(infer_schema(dots[[1]]))
+ }
+
+ Schema$create(...)
Review Comment:
As above, if you feel strongly about this I think it is a better fit for
another PR: our usage everywhere else in the package is to capture the dots
once using `list2()` and use `!!!` if they need to be passed on to another
function.
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