ianmcook commented on a change in pull request #9745:
URL: https://github.com/apache/arrow/pull/9745#discussion_r598781846
##########
File path: r/tests/testthat/helper-data.R
##########
@@ -134,3 +134,17 @@ example_with_logical_factors <- tibble::tibble(
"hey buddy"
)
)
+
+# the values in each column of this tibble are in ascending order in the C
locale.
+# there are some ties, but sorting by any two columns will give a
deterministic order.
+example_data_for_sorting <- tibble::tibble(
+ int = c(-.Machine$integer.max, -101L, -100L, 0L, 0L, 1L, 100L, 1000L,
.Machine$integer.max, NA_integer_),
+ dbl = c(-Inf, -.Machine$double.xmax, -.Machine$double.xmin, 0,
.Machine$double.xmin, pi, .Machine$double.xmax, Inf, NaN, NA_real_),
+ # R string collation varies by locale, while libarrow always uses the C
locale for string collation
+ # (in other words: string values in libarrow are ordered lexicographically
as bytestrings)
+ # to make R sort functions use the C locale, run Sys.setlocale("LC_COLLATE",
"C")
Review comment:
Confirmed it does, and this is mentioned at
https://testthat.r-lib.org/reference/local_test_context.html#details. I
improved this comment in 7b64d1ff18b4f587313be212fc0816e55a54a754.
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