ARROW-13888: [R] Rephrase docs for schema()'s ellipses argument and rephrase error message

r/NAMESPACE

@@ -332,6 +332,7 @@ importFrom(rlang,is_character)
 importFrom(rlang,is_false)
 importFrom(rlang,is_integerish)
 importFrom(rlang,is_interactive)
+importFrom(rlang,is_list)
 importFrom(rlang,is_quosure)
 importFrom(rlang,list2)
 importFrom(rlang,new_data_mask)

r/R/arrow-package.R

@@ -23,6 +23,7 @@
 #' @importFrom rlang eval_tidy new_data_mask syms env new_environment env_bind set_names exec
 #' @importFrom rlang is_bare_character quo_get_expr quo_get_env quo_set_expr .data seq2 is_interactive
 #' @importFrom rlang expr caller_env is_character quo_name is_quosure enexpr enexprs as_quosure
+#' @importFrom rlang is_list
 #' @importFrom tidyselect vars_pull vars_rename vars_select eval_select
 #' @useDynLib arrow, .registration = TRUE
 #' @keywords internal

r/R/schema.R

@@ -18,7 +18,7 @@
 #' @include arrow-package.R
 #' @title Schema class
 #'
-#' @description A `Schema` is a list of [Field]s, which map names to
+#' @description A `Schema` is an Arrow object containing [Field]s, which map names to
 #' Arrow [data types][data-type]. Create a `Schema` when you
 #' want to convert an R `data.frame` to Arrow but don't want to rely on the
 #' default mapping of R types to Arrow types, such as when you want to choose a
@@ -78,6 +78,14 @@
 #' @rdname Schema
 #' @name Schema
 #' @examplesIf arrow_available()
+#' schema(a = int32(), b = float64())
+#'
+#' schema(
+#'   field("b", double()),
+#'   field("c", bool(), nullable = FALSE),
+#'   field("d", string())
+#' )
+#'
 #' df <- data.frame(col1 = 2:4, col2 = c(0.1, 0.3, 0.5))
 #' tab1 <- arrow_table(df)
 #' tab1$schema
@@ -155,6 +163,12 @@ Schema <- R6Class("Schema",
 )
 Schema$create <- function(...) {
   .list <- list2(...)
+
+  # if we were provided only a list of types or fields, use that
+  if (length(.list) == 1 && is_list(.list[[1]])) {
+    .list <- .list[[1]]
+  }
+
   if (all(map_lgl(.list, ~ inherits(., "Field")))) {
     schema_(.list)
   } else {
@@ -185,8 +199,7 @@ print_schema_fields <- function(s) {
   paste(map_chr(s$fields, ~ .$ToString()), collapse = "\n")
 }
 
-#' @param ... named list containing [data types][data-type] or
-#'   a list of [fields][field] containing the fields for the schema
+#' @param ... [fields][field] or field name/[data type][data-type] pairs
 #' @export
 #' @rdname Schema
 schema <- Schema$create

r/tests/testthat/test-schema.R

@@ -40,9 +40,13 @@ test_that("Schema print method", {
 
 test_that("Schema with non-nullable fields", {
   expect_output(
-    print(schema(field("b", double()),
-                 field("c", bool(), nullable = FALSE),
-                 field("d", string()))),
+    print(
+      schema(
+        field("b", double()),
+        field("c", bool(), nullable = FALSE),
+        field("d", string())
+      )
+    ),
     paste(
       "Schema",
       "b: double",
@@ -218,3 +222,19 @@ test_that("Schema to C-interface", {
   # must clean up the pointer or we leak
   delete_arrow_schema(ptr)
 })
+
+test_that("Schemas from lists", {
+  name_list_schema <- schema(list(b = double(), c = string(), d = int8()))
+
+
+  field_list_schema <- schema(
+    list(
+      field("b", double()),
+      field("c", bool()),
+      field("d", string())
+    )
+  )
+
+  expect_equal(name_list_schema, schema(b = double(), c = string(), d = int8()))
+  expect_equal(field_list_schema, schema(b = double(), c = bool(), d = string()))
+})