nealrichardson commented on a change in pull request #11176:
URL: https://github.com/apache/arrow/pull/11176#discussion_r712490536
##########
File path: r/tests/testthat/test-dplyr.R
##########
@@ -989,19 +989,98 @@ test_that("sign()", {
)
})
-test_that("ceiling(), floor(), trunc()", {
+test_that("ceiling(), floor(), trunc(), round()", {
df <- tibble(x = c(-1, -0.55, -0.5, -0.1, 0, 0.1, 0.5, 0.55, 1, NA, NaN))
expect_dplyr_equal(
input %>%
mutate(
c = ceiling(x),
f = floor(x),
- t = trunc(x)
+ t = trunc(x),
+ r = round(x)
) %>%
collect(),
df
)
+
+ # with digits set to 1
+ expect_dplyr_equal(
+ input %>%
+ filter(x %% 0.5 == 0) %>% # filter out indeterminate cases (see below)
+ mutate(r = round(x, 1)) %>%
+ collect(),
+ df
+ )
+
+ # with digits set to -1
+ expect_dplyr_equal(
+ input %>%
+ mutate(
+ rd = round(floor(x * 111), -1), # double
+ y = ifelse(is.nan(x), NA_integer_, x),
+ ri = round(as.integer(y * 111), -1) # integer (with the NaN removed)
+ ) %>%
+ collect(),
+ df
+ )
+
+ # round(x, -2) is equivalent to round_to_multiple(x, 100)
+ expect_equal(
+ Table$create(x = 1111.1) %>%
+ mutate(r = round(x, -2)) %>%
+ collect(),
+ Table$create(x = 1111.1) %>%
+ mutate(r = arrow_round_to_multiple(x, options = list(multiple = 100)))
%>%
+ collect()
+ )
+
+ # For consistency with base R, the binding for round() uses the Arrow
+ # library's HALF_TO_EVEN round mode, but the expectations *above* would pass
+ # even if another round mode were used. The expectations *below* should fail
+ # with other round modes. However, some decimal numbers cannot be represented
+ # exactly as floating point numbers, and for the ones that also end in 5
(such
+ # as 0.55), R's rounding behavior is indeterminate: it will vary depending on
Review comment:
🤯 It's a wonder we ever get anything done
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