fsaintjacques commented on a change in pull request #7435:
URL: https://github.com/apache/arrow/pull/7435#discussion_r440369138
##########
File path: r/src/array_from_vector.cpp
##########
@@ -201,6 +201,39 @@ struct VectorToArrayConverter {
return Status::OK();
}
+ template <typename T>
+ arrow::enable_if_t<arrow::is_struct_type<T>::value, Status> Visit(const T&
type) {
+ using BuilderType = typename TypeTraits<T>::BuilderType;
+ ARROW_RETURN_IF(!Rf_inherits(x, "data.frame"),
+ Status::RError("Expecting a data frame"));
+
+ auto* struct_builder = checked_cast<BuilderType*>(builder);
+
+ int64_t n = 0;
+ if (XLENGTH(x) > 0) {
+ // TODO: need a more generic way to get the vec_size(<data.frame>)
+ // perhaps using vctrs::::short_vec_size
+ n = XLENGTH(VECTOR_ELT(x, 0));
+ }
+ RETURN_NOT_OK(struct_builder->Reserve(n));
+
+ // TODO: double check but seems fine that no value is NULL
Review comment:
You can remove the TODO, this is correct.
##########
File path: r/tests/testthat/test-Array.R
##########
@@ -445,6 +445,9 @@ test_that("Array$create() handles vector -> list arrays
(ARROW-7662)", {
expect_array_roundtrip(list(character(0)), list_of(utf8()))
expect_array_roundtrip(list("itsy", c("bitsy", "spider"), c("is")),
list_of(utf8()))
expect_array_roundtrip(list("itsy", character(0), c("bitsy", "spider",
NA_character_), c("is")), list_of(utf8()))
+
+ # struct
+ expect_array_roundtrip(list(tibble::tibble(a = integer(0))),
list_of(struct(a = int32())))
Review comment:
Add a bit more columns: float, string, bool. Also add a failing case
where columns are not of the same size.
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