Break (bin) selection algorithms for histograms

Methods for determining breaks (bins) in histograms, as used in the breaks argument to density_histogram(). Supports automatic partial function application.

breaks_fixed(x, weights = NULL, width = 1)

breaks_Sturges(x, weights = NULL)

breaks_Scott(x, weights = NULL)

breaks_FD(x, weights = NULL, digits = 5)

Arguments

x

A numeric vector giving a sample.

weights

A numeric vector of length(x) giving sample weights.

width

For breaks_fixed(), the desired bin width.

digits

Number of significant digits to keep when rounding in the Freedman-Diaconis algorithm (breaks_FD()). For an explanation of this parameter, see the documentation of the corresponding parameter in grDevices::nclass.FD().

Value

Either a single number (giving the number of bins) or a vector giving the edges between bins.

Details

These functions take a sample and its weights and return a valuable suitable for the breaks argument to density_histogram() that will determine the histogram breaks.

• breaks_fixed() allows you to manually specify a fixed bin width.

• breaks_Sturges(), breaks_Scott(), and breaks_FD() implement weighted versions of the corresponding base functions. See nclass.Sturges(), nclass.scott(), and nclass.FD().

See also

density_histogram(), align

Examples

library(ggplot2)

set.seed(1234)
x = rnorm(200, 1, 2)

# Let's compare the different break-selection algorithms on this data:
ggplot(data.frame(x), aes(x)) +
  stat_slab(
    aes(y = "breaks_fixed(width = 0.5)"),
    density = "histogram",
    breaks = breaks_fixed(width = 0.5),
    outline_bars = TRUE,
    color = "black",
  ) +
  stat_slab(
    aes(y = "breaks_Sturges()\nor 'Sturges'"),
    density = "histogram",
    breaks = "Sturges",
    outline_bars = TRUE,
    color = "black",
  ) +
  stat_slab(
    aes(y = "breaks_Scott()\nor 'Scott'"),
    density = "histogram",
    breaks = "Scott",
    outline_bars = TRUE,
    color = "black",
  ) +
  stat_slab(
    aes(y = "breaks_FD()\nor 'FD'"),
    density = "histogram",
    breaks = "FD",
    outline_bars = TRUE,
    color = "black",
  ) +
  geom_point(aes(y = 0.7), alpha = 0.5) +
  labs(
    subtitle = "ggdist::stat_slab(density = 'histogram', ...)",
    y = "breaks =",
    x = NULL
  )