Replace bubbles/points in scatterplot by circular barplot

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While trying to visualise some data, I encountered the challenge to display circular barplots in a scatterplot.

Being used to ggplot2, I'm able to draw circular barplots, a scatterplot, but was not able to find a way to combine both of them.

I'd like to replace the points in the scatterplot, by the circular barplots.

Any ideas? Maybe another library?

Below a sample code:

library(ggplot2)

df1 <- structure(list(P = c(1L, 1L, 1L, 2L, 2L, 2L),
                      A = c(2L, 2L, 2L, 4L, 4L, 4L),
                      B = c(2L, 2L, 2L, 3L, 3L, 3L), 
                      C = c(1L, 2L, 3L, 1L, 2L, 3L), 
                      D = c(1L, 3L, 1L, 4L, 5L, 1L)),
                 row.names = c(NA,-6L), class = "data.frame")
scatter_plot <- ggplot(df1, aes(x=A, y=B)) +
  geom_point()

circular_barplot <- ggplot(df1, aes(x=C,y=D)) +
  geom_bar(stat="identity") +
  coord_polar(start=0) +
  facet_wrap(~P)

Output:
scatter_plot: scatter_plot

circular barplot circular_barplot

ggplot2 r
1 Answers

One approach would be to use ggforce::geom_arc_bar which allows to add pies in cartesian coordinates. Note that by code below is a quick and dirty approach to achieve your desired result for your example data.

Basically I first do some data wrangling to get the start and end for the wedges as well as the radius. Afterwards I split the data and add the circular bars via multiple ggforce::geom_arc_bars. I added two parameters r.max to set maximum radius and offset to set the amount of "padding" between the "bars".

library(ggplot2)
library(ggforce)
library(dplyr)

circular_barplot <- function(.data, r.max = .2, offset = .1) {
  .data <- .data |> 
    mutate(start = (C - 1) * 2 * pi / max(C) + offset,
           end = C * 2 * pi / max(C) - offset,
           r = D / max(D) * r.max)
  .data_split <- split(.data, .data$P)
  
  lapply(.data_split, function(.data) {
    x0 <- unique(.data$A)
    y0 <- unique(.data$B)
    geom_arc_bar(aes(
      x0 = x0, y0 = y0, r0 = 0, r = r, start = start, end = end, fill = factor(C)),
      data = .data
    )  
  })
}

ggplot() +
  circular_barplot(df1) +
  coord_fixed()

user_129938610
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