CODEWITHSUNDEEP
rggplot2
Volkerballoon
Volkerballoon

Reputation: 11

Split violin plot with one group using ggplot

To create a split violin plot in ggplot, I have used the geom_split_violin function created by jan-glx below. This function is very handy for two or more groups, and I was wondering if there was a way to utilize this function for only one group? I am aiming to create a split violin plot where the only categorical variable is gender (male/female).

GeomSplitViolin <- ggproto("GeomSplitViolin", GeomViolin, 
                           draw_group = function(self, data, ..., draw_quantiles = NULL) {
  data <- transform(data, xminv = x - violinwidth * (x - xmin), xmaxv = x + violinwidth * (xmax - x))
  grp <- data[1, "group"]
  newdata <- plyr::arrange(transform(data, x = if (grp %% 2 == 1) xminv else xmaxv), if (grp %% 2 == 1) y else -y)
  newdata <- rbind(newdata[1, ], newdata, newdata[nrow(newdata), ], newdata[1, ])
  newdata[c(1, nrow(newdata) - 1, nrow(newdata)), "x"] <- round(newdata[1, "x"])

  if (length(draw_quantiles) > 0 & !scales::zero_range(range(data$y))) {
    stopifnot(all(draw_quantiles >= 0), all(draw_quantiles <=
      1))
    quantiles <- ggplot2:::create_quantile_segment_frame(data, draw_quantiles)
    aesthetics <- data[rep(1, nrow(quantiles)), setdiff(names(data), c("x", "y")), drop = FALSE]
    aesthetics$alpha <- rep(1, nrow(quantiles))
    both <- cbind(quantiles, aesthetics)
    quantile_grob <- GeomPath$draw_panel(both, ...)
    ggplot2:::ggname("geom_split_violin", grid::grobTree(GeomPolygon$draw_panel(newdata, ...), quantile_grob))
  }
  else {
    ggplot2:::ggname("geom_split_violin", GeomPolygon$draw_panel(newdata, ...))
  }
})

geom_split_violin <- function(mapping = NULL, data = NULL, stat = "ydensity", position = "identity", ..., 
                              draw_quantiles = NULL, trim = TRUE, scale = "area", na.rm = FALSE, 
                              show.legend = NA, inherit.aes = TRUE) {
  layer(data = data, mapping = mapping, stat = stat, geom = GeomSplitViolin, 
        position = position, show.legend = show.legend, inherit.aes = inherit.aes, 
        params = list(trim = trim, scale = scale, draw_quantiles = draw_quantiles, na.rm = na.rm, ...))
}

ggplot(my_data, aes(x, y, fill = m)) + geom_split_violin()

Upvotes: 1

Views: 745

Answers (2)

Peng
Peng

Reputation: 11

ggplot(data = data%>%mutate(my_group = "Group"), 
       aes_string(x = "my_group", 
                  y = yvar,
                  color = "yoad_load",
                  fill = "yoad_load"))+
  #geom_split_violin will leave a gap if you only have one 
grouping variable so have to make an extra one for x-axis 
position
    introdataviz::geom_split_violin(alpha = 0.4, 
      trim = FALSE, #don't trim the tails 
      draw_quantiles = NULL, 
      scale = "area", 
      linetype = "solid", linewidth = 0.5)+
    ggplot2::geom_boxplot(
      width = 0.2, size = 0.2, 
      na.rm = TRUE, show.legend = FALSE, fill = "white", alpha = 0.4,
      outlier.size = 0.5, outlier.alpha = 0.3, outlier.shape = NA)

Upvotes: 0

danlooo
danlooo

Reputation: 10627

There is geom_violinhalf from the see package:

library(tidyverse)
library(see)

ggplot(iris, aes(x = "x", y = Sepal.Length, fill = Species)) +
  geom_violinhalf(
    data = iris %>% filter(Species == "setosa")
  ) +
  geom_violinhalf(
    data = iris %>% filter(Species == "versicolor"),
    flip = TRUE
  )

Created on 2021-11-25 by the reprex package (v2.0.1)

Upvotes: 0

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