a generic number formatter

cf. r-lib#142

NEWS.md

@@ -22,6 +22,8 @@
 
 * Function `colour_ramp()` now uses `alpha = TRUE` by default (@clauswilke, #108).
 
+* New function `number_format()`, a generic formatter for numbers (@larmarange, #142).
+
 # scales 0.5.0
 
 * New function `regular_minor_breaks()` calculates minor breaks as a property

R/formatter.r

@@ -1,20 +1,19 @@
 #' Number formatter: a generic formatter for numbers
 #'
 #' @return `number_format` returns a function with single parameter
-#' `x`, a numeric vector, that returns a character vector
-#' @param x a numeric vector to format
-#' @param accuracy number to round to, `NULL` for automatic guess
-#' @param scale a scaling factor: `x` will be multiply by `scale` before
-#' formating (useful if the underlying data is on another scale,
-#' e.g. for computing percentages or thousands)
-#' @param prefix,suffix symbols to display before and after value
-#' @param big.mark character used between every 3 digits to separate thousands,
-#' a comma by default or a space if comma is already used for `decimal.mark`
-#' @param decimal.mark the character to be used to indicate the numeric
-#' decimal point
-#' @param trim logical, if `FALSE`, values are right-justified to a common
-#' width (see [base::format()])
-#' @param ... other arguments passed on to [base::format()]
+#'   `x`, a numeric vector, that returns a character vector.
+#' @param x A numeric vector to format.
+#' @param accuracy Number to round to, `NULL` for automatic guess.
+#' @param scale A scaling factor: `x` will be multiply by `scale` before
+#'   formating (useful if the underlying data is on another scale,
+#'   e.g. for computing percentages or thousands).
+#' @param prefix,suffix Symbols to display before and after value.
+#' @param big.mark Character used between every 3 digits to separate thousands.
+#' @param decimal.mark The character to be used to indicate the numeric
+#'   decimal point.
+#' @param trim Logical, if `FALSE`, values are right-justified to a common
+#'   width (see [base::format()]).
+#' @param ... Other arguments passed on to [base::format()].
 #' @export
 #' @examples
 #' v <- c(12.3, 4, 12345.789, 0.0002)
@@ -35,7 +34,7 @@
 #' )
 #' per_mille(v)
 number_format <- function(accuracy = 1, scale = 1, prefix = "",
-                          suffix = "", big.mark = NULL, decimal.mark = ".",
+                          suffix = "", big.mark = " " , decimal.mark = ".",
                           trim = TRUE, ...) {
   function(x) number(
       x,
@@ -53,18 +52,14 @@ number_format <- function(accuracy = 1, scale = 1, prefix = "",
 #' @export
 #' @rdname number_format
 number <- function(x, accuracy = 1, scale = 1, prefix = "",
-                   suffix = "", big.mark = NULL, decimal.mark = ".",
+                   suffix = "", big.mark = " ", decimal.mark = ".",
                    trim = TRUE, ...) {
   if (length(x) == 0) return(character())
   accuracy <- accuracy %||% precision(x)
   x <- round_any(x, accuracy / scale)
   nsmall <- -floor(log10(accuracy))
   nsmall <- min(max(nsmall, 0), 20)
 
-  if (is.null(big.mark)) {
-    big.mark = if (identical(decimal.mark, ",")) " " else ","
-  }
-
   ret <- format(
     scale * x,
     big.mark = big.mark,

tests/testthat/test-formatter.r

@@ -14,20 +14,16 @@ test_that("number format works correctly", {
   expect_equal(number(123.45, accuracy = 10), "120")
   expect_equal(number(123.45, accuracy = .25), "123.5")
   expect_equal(
-    number(12345, big.mark = "'"),
-    "12'345"
+    number(12345, big.mark = ","),
+    "12,345"
   )
   expect_equal(
     number(12.3, decimal.mark = ",", accuracy = .1),
     "12,3"
   )
   expect_equal(
-    number(12345.6, decimal.mark = ",", accuracy = .1),
-    "12 345,6"
-  )
-  expect_equal(
-    number(1.234, scale = 1000),
-    "1,234"
+    number(1.234, scale = 100),
+    "123"
   )
   expect_equal(
     number(123, prefix = "pre", suffix = "post"),