Address floating point imprecision in round_half_up() #396 (#399)

* fix #396
sfirke · Aug 18, 2020 · cbafdd1 · cbafdd1
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diff --git a/NEWS.md b/NEWS.md
@@ -2,6 +2,8 @@
 
 ## Bug fixes
 
+* Fixed rounding issue in round_half_up() function (#396, thanks to @JJSteph)
+
 * Warnings for incomplete argument names are fixed (fix #367, thanks to @pabecerra for reporting and @billdenney for fixing)
 
 * 3-way tabyls with factors have columns and rows sorted in the correct order, by factor level (#379).

diff --git a/R/round_half_up.R b/R/round_half_up.R
@@ -17,7 +17,7 @@
 round_half_up <- function(x, digits = 0) {
   posneg <- sign(x)
   z <- abs(x) * 10 ^ digits
-  z <- z + 0.5
+  z <- z + 0.5 + sqrt(.Machine$double.eps)
   z <- trunc(z)
   z <- z / 10 ^ digits
   z * posneg

diff --git a/tests/testthat/test-utilities.R b/tests/testthat/test-utilities.R
@@ -10,4 +10,5 @@ test_that("round_half_up works", {
   expect_equal(round_half_up(0.5, 0), 1)
   expect_equal(round_half_up(1.125, 2), 1.13)
   expect_equal(round_half_up(1.135, 2), 1.14)
-})
+  expect_equal(round_half_up(2436.845, 2), 2436.85)
+})