Add fanchart to ggplot

The fanchart is obtained by overlaying ggplot2::geom_ribbon() of different widths (corresponding to different levels). This function is not a geom.

Usage

add_fanchart(
  df,
  aes_x = "Time",
  aes_ymin = "Lower",
  aes_ymax = "Upper",
  aes_fill = "Level",
  legend_fill = c("continuous", "discrete"),
  labs_fill = ifelse(legend_fill == "continuous", "Confidence level", "Probability"),
  palette = c("#EFF3FF", "#C6DBEF", "#9ECAE1", "#6BAED6", "#3182BD", "#08519C")
)

Arguments

df

Data with columns aes_x, aes_ymin, aes_ymax and aes_fill

aes_x

Name of the x aesthetic

aes_ymin

Name of the ymin aesthetic

aes_ymax

Name of the ymax aesthetic

aes_fill

Name of the fill aesthetic

legend_fill

Whether the legend should be displayed as continuous or as discrete categories

labs_fill

Name to give to the legend

palette

Colour palette to use. The default is the single-hue blue palette from RColorBrewer::brewer.pal(n = 6, "Blues").

Value

List to be added to a ggplot

Alternative

A similar result can be obtained using ggdist::geom_lineribbon(), with the difference that the ggdist function also plots a point estimate (and is a proper geom). To avoid plotting the point estimate, size can be set to 0 and y = .lower for example.

Examples

library(dplyr)
library(tidyr)
library(ggplot2)

tmp <- tibble(Time = 0:10,
              y = Time^1.5) %>%
  expand_grid(Level = seq(0.1, 0.9, 0.2)) %>%
  mutate(Width = qnorm(0.5 + Level / 2, sd = 2),
         Lower = y - Width,
         Upper = y + Width)
ggplot() + add_fanchart(tmp)