Copilot commented on code in PR #50374:
URL: https://github.com/apache/arrow/pull/50374#discussion_r3544714217
##########
r/vignettes/data_types.Rmd:
##########
@@ -97,9 +97,10 @@ If the value in R does not fall within the permissible range
for the correspondi
chunked_array(c(10L, 3L, 200L), type = int8())
```
-When translating from Arrow to R, integer types alway translate to R integers
unless one of the following exceptions applies:
+When translating from Arrow to R, integer types always translate to R integers
unless one of the following exceptions applies:
-- If the value of an Arrow uint32 or uint64 falls outside the range allowed
for R integers, the result will be a numeric vector in R
+- Arrow uint64 types are always converted to numeric (double) vectors in R
Review Comment:
The new mapping “uint64 → R numeric (double)” is correct for type
unification, but it can still silently lose integer precision once values
exceed 2^53 (because R numeric is IEEE-754 double). It would help to mention
this explicitly here so users don’t assume all uint64 values round-trip exactly.
##########
r/R/type.R:
##########
@@ -356,13 +356,13 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' `date32()` creates a datetime type with a "day" unit, like the R `Date`
#' class. `date64()` has a "ms" unit.
#'
-#' `uint32` (32 bit unsigned integer), `uint64` (64 bit unsigned integer), and
-#' `int64` (64-bit signed integer) types may contain values that exceed the
-#' range of R's `integer` type (32-bit signed integer). When these arrow
objects
-#' are translated to R objects, `uint32` and `uint64` are converted to `double`
-#' ("numeric") and `int64` is converted to `bit64::integer64`. For `int64`
-#' types, this conversion can be disabled (so that `int64` always yields a
-#' `bit64::integer64` object) by setting `options(arrow.int64_downcast =
+#' `uint64` (64 bit unsigned integer) is always converted to `double`
+#' ("numeric") in R. `uint32` (32 bit unsigned integer) and `int64` (64-bit
+#' signed integer) types may contain values that exceed the range of R's
+#' `integer` type (32-bit signed integer). When they do, `uint32` is converted
+#' to `double` ("numeric") and `int64` is converted to `bit64::integer64`. For
Review Comment:
This documentation states that `uint64` is always converted to `double`, but
it doesn’t mention that doubles can’t exactly represent all 64-bit integers
(precision loss above 2^53). Adding that clarification would set expectations
for users relying on large identifiers.
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