Color Quantile from a density in ggplot2 with labeled quantiles

ColoredQuant_ggplot2.R

# Script from a density to color quantiles area

# Packages ---------------------------------------------------------------------
library(ggplot2)
library(dplyr)

# Data -------------------------------------------------------------------------
r_data = rnorm(100)  # Computes 100 values

r_quant = quantile(r_data, probs = seq(0, 1, 0.1))  # Computes quantiles

# Make a df with column x & y extracted from density object
dens = with(density(r_data), data.frame(x, y)) %>%
  filter(x >= r_quant[1], x <= r_quant[length(r_quant)])

# Add columns to classify by quantile
dens$quant = cut(dens$x, breaks = r_quant)

# Get names of quantiles (i.e. '10%', etc.)
q_names = names(r_quant)

# Make a vector of potential labels of quantiles (i.e. '0%-10%'
q_labels = paste(q_names[-length(q_names)], q_names[-1], sep = "-")


# Plot -------------------------------------------------------------------------

# Basic Plot
p_dens = ggplot(dens, aes(x = x, y = y)) +
  geom_area(aes(fill = quant)) +
  geom_line(size = 2)

# Plot with diverging color scale around 50% quantile
p_dens + scale_fill_brewer(palette = "PuOr")

# Plot with diverging color scale and nicely labeled quantiles
p_dens + scale_fill_brewer(palette = "PuOr", labels = q_labels)