create.violinplot: how to add extra points when using panels?

[jarbet]

I'm trying to add median points to a violin plot when having multiple panels: i.e. formula = outcome ~ first.group.var | second.group.var.

I can't figure out how to get the extra.points argument to work with panels, but I found a workaround using + layer(panel.points(..)):

suppressPackageStartupMessages(library(BoutrosLab.plotting.general));

set.seed(12345);
n <- 1090;
simple.data <- data.frame(
    outcome = c(
        rnorm(n = n/2, mean = 0),
        rnorm(n = n/2, mean = 3)
        ),
    first.group.var = as.factor(sample(LETTERS[1:2],n,TRUE))
    );
simple.data$second.group.var <- c(
    rep('group.1', n / 2),
    rep('group.2', n / 2)
    );

medians <- aggregate(
    x = outcome ~ first.group.var + second.group.var,
    data = simple.data,
    FUN = median
    );

Attempt 1: try passing vector to extra.points

create.violinplot(
    formula = outcome ~ first.group.var | second.group.var,
    resolution = 100,
    data = simple.data,
    extra.points = medians$outcome,
    extra.points.pch = 21,
    extra.points.col = c('blue'),
    extra.points.cex = 1.5,
    xlab.label = ''
    );

Attempt 2: try passing list to extra.points, one vector per panel

create.violinplot(
    formula = outcome ~ first.group.var | second.group.var,
    resolution = 100,
    data = simple.data,
    extra.points = list(
        medians$outcome[medians$second.group.var == 'group.1'],
        medians$outcome[medians$second.group.var == 'group.2']
        ),
    extra.points.pch = 21,
    extra.points.col = c('blue'),
    extra.points.cex = 1.5,
    xlab.label = ''
    );

Solution using + layer(panel.points(...))

violin <- create.violinplot(
    formula = outcome ~ first.group.var | second.group.var,
    resolution = 100,
    data = simple.data,
    );
extra.points.x <- list(1:2, 1:2);
extra.points.y <- list(
        medians$outcome[medians$second.group.var == 'group.1'],
        medians$outcome[medians$second.group.var == 'group.2']
        );
violin + layer(panel.points(
    x = extra.points.x[[panel.number()]],
    y = extra.points.y[[panel.number()]],
    pch = 21,
    col = 'blue',
    fill = 'blue',
    cex = 1.5
    ))

^{Created on 2024-05-31 with reprex v2.0.2}