edponce commented on a change in pull request #11133:
URL: https://github.com/apache/arrow/pull/11133#discussion_r707458749
##########
File path: r/tests/testthat/test-dplyr.R
##########
@@ -1035,10 +1035,20 @@ test_that("log functions", {
df
)
- expect_error(
- nse_funcs$log(Expression$scalar(x), base = 5),
- "`base` values other than exp(1), 2 and 10 not supported by Arrow",
- fixed = TRUE
+ expect_dplyr_equal(
+ input %>%
+ mutate(y = log(x, base = 5)) %>%
+ collect(),
+ df
+ )
+
+ expect_dplyr_equal(
+ input %>%
+ # suppress 'NaNs produced' warning on the first row of df
+ # that evaluates to NaN (R raises warning but Arrow does not)
+ suppressWarnings(mutate(., y = log(x, base = x))) %>%
Review comment:
log(x) with base 1 is not a reasonable calculation because this implies
solving the following equation `1^y = x` which is only defined for `x = 1`.
Nevertheless, most math libraries will yield a value of infinity for base 1
logarithms regardless of `x`. Arrow C++ follows this scheme.
These cases are missing from the tests.
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