This is a basic function to create R ggplot2 boxplots with square axes. The 1:1 length ratio of the y-axis and x-axis is preserved even after grouping multiple graphs using facets. Users can define the y axis range and intervals.

This packages requires ggplot2

install.packages("ggplot2")

Install using following commands:

library(devtools)
devtools::install_github("daviszhou/sbplot")

The main function is boxplot_square_axis(), which returns a plot object. Example usage:

library(sbplot)

xaxis = c('Controls', 'Study Group')
ymin = 0
ymax = 1
yinterval = 0.5
yaxis = seq(ymin, ymax, yinterval)
whiskers = c(0.10, 0.90)
                 
p <- boxplot_square_axis(data, xaxis_category, yaxis_category, xaxis, yaxis, custom_whiskers=whiskers,
  color_category=NULL,
  color_scale=NULL,
  color_labels=NULL,
  change_fill_color=TRUE,
  font_size=10)

Function Arguments:

• data: Data frame containing desired variables.
• xaxis_category: Name of data frame column that contains the factors for x-axis categories.
• yaxis_category: Name of data frame column that contains values for the y-axis.
• xaxis: Custom labels for the x-axis. Set using xaxis = c('X Group 1', 'X Group 2').
• yaxis: Specify the range and interval of the y-axis. Set using yaxis = seq(y_min, y_max, y_interval).
• custom_whiskers: Specifies custom percentiles for boxplot whiskers. Set using custom_whiskers = c(lower_whisker_percentile, upper_whisker_percentile). Set as "NULL" for the traditional method, which uses the farthest value within 1.5*IQR from the upper and lower hinges of the boxplot. By default set to "NULL". [OPTIONAL]
• color_category: Name of the data frame column that contains the factors used to separate groups by boxplot color. To plot without subcategories sorted by color, set variable as "NULL". [OPTIONAL]
• color_labels: Vector of color category subgroup names. Set using color_labels = c("Color Group 1", "Color Group 2"). By default will use data frame factor names. [OPTIONAL]
• change_fill_color: Determines whether to change the boxplot fill or line color if color_category is provided. By defualt set to "TRUE" to change the fill color.
• font_size: Integer to determine text size of the title, axes, and axes labels.