histogram_by_group function

Histogram by group

Creates histograms by group to compare distributions.

histogram_by_group(
  data = NULL,
  iv_name = NULL,
  dv_name = NULL,
  order_of_groups_top_to_bot = NULL,
  number_of_bins = 40,
  space_between_histograms = 0.15,
  draw_baseline = FALSE,
  xlab = NULL,
  ylab = NULL,
  x_limits = NULL,
  x_breaks = NULL,
  x_labels = NULL,
  sigfigs = 3,
  convert_dv_to_numeric = TRUE
)

Arguments

• data: a data object (a data frame or a data.table)
• iv_name: name of the independent variable
• dv_name: name of the dependent variable
• order_of_groups_top_to_bot: a character vector indicating the desired presentation order of levels in the independent variable (from the top to bottom). Omitting a group in this argument will remove the group in the set of histograms.
• number_of_bins: number of bins for the histograms (default = 40)
• space_between_histograms: space between histograms (minimum = 0, maximum = 1, default = 0.15)
• draw_baseline: logical. Should the baseline and the trailing lines to either side of the histogram be drawn? (default = FALSE)
• xlab: title of the x-axis for the histogram by group. If xlab = FALSE, the title will be removed. By default (i.e., if no input is given), dv_name will be used as the title.
• ylab: title of the y-axis for the histogram by group. If ylab = FALSE, the title will be removed. By default (i.e., if no input is given), iv_name will be used as the title.
• x_limits: a numeric vector with values of the endpoints of the x axis.
• x_breaks: a numeric vector indicating the points at which to place tick marks on the x axis.
• x_labels: a vector containing labels for the place tick marks on the x axis.
• sigfigs: number of significant digits to round to (default = 3)
• convert_dv_to_numeric: logical. Should the values in the dependent variable be converted to numeric for plotting the histograms? (default = TRUE)

Returns

the output will be a set of vertically arranged histograms (a ggplot object), i.e., one histogram for each level of the independent variable.

Details

The following package(s) must be installed prior to running this function: Package 'ggridges' v0.5.3 (or possibly a higher version) by Claus O. Wilke (2021), https://cran.r-project.org/package=ggridges

Examples

histogram_by_group(data = mtcars, iv_name = "cyl", dv_name = "mpg")
histogram_by_group(
  data = mtcars, iv_name = "cyl", dv_name = "mpg",
  order_of_groups_top_to_bot = c("8", "4"), number_of_bins = 10,
  space_between_histograms = 0.5
)
histogram_by_group(
data = iris, iv_name = "Species", dv_name = "Sepal.Length", x_breaks = 4:8,
x_limits = c(4, 8))