Violin plots show the full distribution shape using kernel density estimation. They’re ideal for revealing multimodal distributions and comparing distribution shapes across groups.

TipWhen to Use Violin Plots

Best for visualizing distribution shapes when you need to see:

  • Bimodal or multimodal distributions
  • Skewness and asymmetry
  • Detailed distribution comparisons

Use boxplots instead if you only need to compare medians, quartiles, and outliers.

ImportantData Format for Array Columns

Array columns require the I() wrapper to preserve list structure:

# Create a data frame with array column
data <- data.frame(
  group = c("A", "B", "C"),
  values = I(list(
    rnorm(100, mean = 5, sd = 2),
    rnorm(100, mean = 8, sd = 3),
    c(rnorm(50, 4, 1), rnorm(50, 10, 1))  # Bimodal
  ))
)

Without I(), R will try to unlist the vectors and fail.

Basic Usage

Code 
set.seed(456)
violin_data <- data.frame(
  group = c("Young Adults", "Middle Age", "Seniors"),
  scores = I(list(
    c(rnorm(80, 72, 8), rnorm(20, 90, 5)),  # Bimodal
    rnorm(100, 68, 12),                       # Normal
    c(rnorm(70, 60, 10), runif(30, 40, 80))  # Skewed
  )),
  n = c(100, 100, 100)
)

tabviz(violin_data, label = "group",
  columns = list(
    col_n("n"),
    viz_violin(
      effect_violin(data = "scores", color = "#f59e0b"),
      header = "Score Distribution",
      width = 250,
      show_median = TRUE,
      show_quartiles = TRUE
    )
  ),
  title = "Score Distributions by Age Group"
)

Comparing Distributions

Code 
set.seed(789)
compare_violin <- data.frame(
  condition = c("Healthy", "Mild", "Moderate", "Severe"),
  biomarker_a = I(list(
    rnorm(60, 25, 5),
    rnorm(60, 35, 8),
    rnorm(60, 50, 12),
    rnorm(60, 70, 15)
  )),
  biomarker_b = I(list(
    rnorm(60, 30, 6),
    rnorm(60, 40, 7),
    rnorm(60, 55, 10),
    rnorm(60, 65, 18)
  ))
)

tabviz(compare_violin, label = "condition",
  columns = list(
    viz_violin(
      effect_violin(data = "biomarker_a", label = "Biomarker A", color = "#3b82f6"),
      effect_violin(data = "biomarker_b", label = "Biomarker B", color = "#ef4444"),
      header = "Biomarker Distributions",
      width = 280,
      show_median = TRUE
    )
  ),
  title = "Biomarker Profiles by Disease Severity"
)

viz_violin() Arguments

Argument Description Default
header Column header text NULL
width Column width in pixels 150
scale "linear" or "log" "linear"
axis_range Fixed axis range c(min, max) Auto
axis_ticks Custom tick positions Auto
axis_gridlines Show vertical gridlines FALSE
bandwidth KDE bandwidth (NULL = auto via Silverman’s rule) NULL
show_median Show median line TRUE
show_quartiles Show Q1/Q3 dashed lines FALSE
axis_label Label text below axis "Value"
show_axis Show the axis TRUE

effect_violin() Arguments

Argument Description
data Column containing array of values (required)
label Display label for legend
color Violin fill color
fill_opacity Fill opacity (default: 0.5)

See Also