Violin + boxplot with Wilcoxon rank-sum test — plot_numeric_by

Create a violin plot overlaid with a narrow boxplot for two groups and run a Wilcoxon rank-sum test. Returns the ggplot object and a tidy Wilcoxon result.

Usage

plot_numeric_by_2groups(
  yvar,
  group,
  d,
  title = NULL,
  colors = c("white", "white"),
  digits = 1
)

Arguments

yvar: character(1) Name of the numeric outcome column in d.
group: character(1) Name of the factor column in d (must have 2 levels).
d: data.frame Data containing yvar and group.
title: character Optional plot title. If NULL, a default is generated.
colors: character vector Length-2 vector of fill colours (default c('white', 'white')); if NULL the default ggplot2 fill scale is used. When supplied, must be a character vector with length equal to the number of groups (two after filtering); if it has names, they must exactly match the factor levels.
digits: numeric(1) Number of decimal places to use in the subtitle statistics.

Value

A list with elements:

ggplot: A ggplot2 object (violin + boxplot).
wilcox: A tibble with the Wilcoxon test results (from broom::tidy).

Examples

mtcars$am <- factor(mtcars$am)
res <- plot_numeric_by_2groups("mpg", "am", mtcars)
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact confidence intervals with ties
res$ggplot

res$wilcox
#> # A tibble: 1 × 8
#>   estimate statistic p.value conf.low conf.high method       alternative outcome
#>      <dbl>     <dbl>   <dbl>    <dbl>     <dbl> <chr>        <chr>       <chr>  
#> 1    -6.80        42 0.00187    -11.7     -2.90 Wilcoxon ra… two.sided   mpg