Add default value to round five up (#62)

* add extra examples and default dp value

* update error messages to be more specific

* fix typo in round_five_up() documentation

* style round_five_up() code

* change argument from value to number

* Tweak r5u wording based on PR comments to be easier to understand

R/round_five_up.R

@@ -1,33 +1,51 @@
 #' Round five up
 #'
+#' @description
 #' Round any number to a specified number of places, with 5's being rounded up.
-#' This is as an alternative to round in base R, which sometimes rounds 5's
-#' down due to an international standard. For more information see the
-#' round() documentation:
-#' https://stat.ethz.ch/R-manual/R-devel/library/base/html/Round.html
+#'
+#' @details
+#' Rounds to 0 decimal places by default.
 #'
 #' You can use a negative value for the decimal places. For example:
 #' -1 would round to the nearest 10
 #' -2 would round to the nearest 100
 #' and so on.
 #'
-#' @param value number to be rounded
-#' @param dp number of decimal places to round to
+#' This is as an alternative to round in base R, which uses a bankers round.
+#' For more information see the
+#' [round() documentation](https://rdrr.io/r/base/Round.html).
+#'
+#'
+#' @param number number to be rounded
+#' @param dp number of decimal places to round to, default is 0
 #'
 #' @return Rounded number
 #' @export
 #'
 #' @examples
-#' round_five_up(2495, -1)
-#' round_five_up(2495.85, 1)
-round_five_up <- function(value, dp) {
-  if (!is.numeric(value) && !is.numeric(dp)) stop("both inputs must be numeric")
-  if (!is.numeric(value)) stop("the value to be rounded must be numeric")
-  if (!is.numeric(dp)) stop("the decimal places value must be numeric")
+#' # No dp set
+#' round_five_up(2485.85)
+#'
+#' # With dp set
+#' round_five_up(2485.85, 2)
+#' round_five_up(2485.85, 1)
+#' round_five_up(2485.85, 0)
+#' round_five_up(2485.85, -1)
+#' round_five_up(2485.85, -2)
+round_five_up <- function(number, dp = 0) {
+  if (!is.numeric(number) && !is.numeric(dp)) {
+    stop("both input arguments must be numeric")
+  }
+  if (!is.numeric(number)) {
+    stop("the input number to be rounded must be numeric")
+  }
+  if (!is.numeric(dp)) {
+    stop("the decimal places input must be numeric")
+  }
 
-  z <- abs(value) * 10^dp
+  z <- abs(number) * 10^dp
   z <- z + 0.5 + sqrt(.Machine$double.eps)
   z <- trunc(z)
   z <- z / 10^dp
-  return(z * sign(value))
+  return(z * sign(number))
 }

tests/testthat/test-round_five_up.R

@@ -1,32 +1,38 @@
 test_that("Rounds fives up", {
   expect_equal(round_five_up(285, -1), 290)
+  expect_equal(round_five_up(2.85), 3)
+  expect_equal(round_five_up(2.5), 3)
   expect_equal(round_five_up(2.85, 1), 2.9)
 })
 
 test_that("Rounds other numbers", {
-  expect_equal(round_five_up(283, -1), 280)
-  expect_equal(round_five_up(2.87, 1), 2.9)
+  expect_equal(round_five_up(283.54, -2), 300)
+  expect_equal(round_five_up(283.54, -1), 280)
+  expect_equal(round_five_up(283.234, 0), 283)
+  expect_equal(round_five_up(283.234), 283)
+  expect_equal(round_five_up(2.86, 1), 2.9)
+  expect_equal(round_five_up(2.86, 2), 2.86)
 })
 
 test_that("Input validation", {
   expect_error(
     round_five_up("ten", "10"),
-    "both inputs must be numeric"
+    "both input arguments must be numeric"
   )
   expect_error(
     round_five_up(12, "ten"),
-    "the decimal places value must be numeric"
+    "the decimal places input must be numeric"
   )
   expect_error(
     round_five_up(12, "10"),
-    "the decimal places value must be numeric"
+    "the decimal places input must be numeric"
   )
   expect_error(
     round_five_up("twelve", 10),
-    "the value to be rounded must be numeric"
+    "the input number to be rounded must be numeric"
   )
   expect_error(
     round_five_up("12", 10),
-    "the value to be rounded must be numeric"
+    "the input number to be rounded must be numeric"
   )
 })