label_number: Label numbers in decimal format (e.g. 0.12, 1,234)

In hadley/scales: Scale Functions for Visualization

Label numbers in decimal format (e.g. 0.12, 1,234)

Description

Use label_number() to force decimal display of numbers (i.e. don't use scientific notation). label_comma() is a special case that inserts a comma every three digits.

Usage

label_number(
  accuracy = NULL,
  scale = 1,
  prefix = "",
  suffix = "",
  big.mark = NULL,
  decimal.mark = NULL,
  style_positive = NULL,
  style_negative = NULL,
  scale_cut = NULL,
  trim = TRUE,
  ...
)

label_comma(
  accuracy = NULL,
  scale = 1,
  prefix = "",
  suffix = "",
  big.mark = ",",
  decimal.mark = ".",
  trim = TRUE,
  digits,
  ...
)

Arguments

accuracy	A number to round to. Use (e.g.) 0.01 to show 2 decimal places of precision. If NULL, the default, uses a heuristic that should ensure breaks have the minimum number of digits needed to show the difference between adjacent values. Applied to rescaled data.
scale	A scaling factor: x will be multiplied by scale before formatting. This is useful if the underlying data is very small or very large.
prefix	Additional text to display before the number. The suffix is applied to absolute value before style_positive and style_negative are processed so that prefix = "$" will yield (e.g.) ⁠-$1⁠ and ⁠($1)⁠.
suffix	Additional text to display after the number.
big.mark	Character used between every 3 digits to separate thousands. The default (NULL) retrieves the setting from the number options.
decimal.mark	The character to be used to indicate the numeric decimal point. The default (NULL) retrieves the setting from the number options.
style_positive	A string that determines the style of positive numbers: "none" (the default): no change, e.g. 1. "plus": preceded by +, e.g. +1. "space": preceded by a Unicode "figure space", i.e., a space equally as wide as a number or +. Compared to "none", adding a figure space can ensure numbers remain properly aligned when they are left- or right-justified. The default (NULL) retrieves the setting from the number options.
style_negative	A string that determines the style of negative numbers: "hyphen" (the default): preceded by a standard hyphen -, e.g. -1. "minus", uses a proper Unicode minus symbol. This is a typographical nicety that ensures - aligns with the horizontal bar of the the horizontal bar of +. "parens", wrapped in parentheses, e.g. (1). The default (NULL) retrieves the setting from the number options.
scale_cut	Named numeric vector that allows you to rescale large (or small) numbers and add a prefix. Built-in helpers include: cut_short_scale(): [10^3, 10^6) = K, [10^6, 10^9) = M, [10^9, 10^12) = B, [10^12, Inf) = T. cut_long_scale(): [10^3, 10^6) = K, [10^6, 10^12) = M, [10^12, 10^18) = B, [10^18, Inf) = T. cut_si(unit): uses standard SI units. If you supply a vector c(a = 100, b = 1000), absolute values in the range ⁠[0, 100)⁠ will not be rescaled, absolute values in the range ⁠[100, 1000)⁠ will be divided by 100 and given the suffix "a", and absolute values in the range ⁠[1000, Inf)⁠ will be divided by 1000 and given the suffix "b". If the division creates an irrational value (or one with many digits), the cut value below will be tried to see if it improves the look of the final label.
trim	Logical, if FALSE, values are right-justified to a common width (see base::format()).
...	Other arguments passed on to base::format().
digits	Use accuracy instead.

Value

All label_() functions return a "labelling" function, i.e. a function that takes a vector x and returns a character vector of length(x) giving a label for each input value.

Labelling functions are designed to be used with the labels argument of ggplot2 scales. The examples demonstrate their use with x scales, but they work similarly for all scales, including those that generate legends rather than axes.

Examples

demo_continuous(c(-1e6, 1e6))
demo_continuous(c(-1e6, 1e6), labels = label_number())
demo_continuous(c(-1e6, 1e6), labels = label_comma())

# Use scale to rescale very small or large numbers to generate
# more readable labels
demo_continuous(c(0, 1e6), labels = label_number())
demo_continuous(c(0, 1e6), labels = label_number(scale = 1 / 1e3))
demo_continuous(c(0, 1e-6), labels = label_number())
demo_continuous(c(0, 1e-6), labels = label_number(scale = 1e6))

#' Use scale_cut to automatically add prefixes for large/small numbers
demo_log10(
  c(1, 1e9),
  breaks = log_breaks(10),
  labels = label_number(scale_cut = cut_short_scale())
)
demo_log10(
  c(1, 1e9),
  breaks = log_breaks(10),
  labels = label_number(scale_cut = cut_si("m"))
)
demo_log10(
  c(1e-9, 1),
  breaks = log_breaks(10),
  labels = label_number(scale_cut = cut_si("g"))
)
# use scale and scale_cut when data already uses SI prefix
# for example, if data was stored in kg
demo_log10(
  c(1e-9, 1),
  breaks = log_breaks(10),
  labels = label_number(scale_cut = cut_si("g"), scale = 1e3)
)

#' # Use style arguments to vary the appearance of positive and negative numbers
demo_continuous(c(-1e3, 1e3), labels = label_number(
  style_positive = "plus",
  style_negative = "minus"
))
demo_continuous(c(-1e3, 1e3), labels = label_number(style_negative = "parens"))

# You can use prefix and suffix for other types of display
demo_continuous(c(32, 212), labels = label_number(suffix = "\u00b0F"))
demo_continuous(c(0, 100), labels = label_number(suffix = "\u00b0C"))

hadley/scales documentation built on June 13, 2025, 3:21 a.m.