Quick start

The gghighlight package in R is an extension of the ggplot2 package, designed to simplify the process of highlighting elements.

It mainly offers a gghighlight() function that highlights geoms.

✍️ author → Hiroaki Yutani

📘 documentation → github

⭐️ more than 500 stars on github

Installation

To get started with gghighlight, you can install it directly from CRAN using the install.packages function:

install.packages("gghighlight")

Basic usage

The gghighlight package allows you to showcase specific elements in your ggplot2 charts.

Here’s a basic example on a line charts with multiple lines. At the end of the usual ggplot2 call, the gghighlight() function is called with a single argument.

This argument is the condition that a group should respect to be highlighted.

library(ggplot2)
library(gghighlight)

# dataset with 3 lines named "a", "b" and "c"
set.seed(1)
period <- 365
df <- data.frame(
  Date = seq(as.Date("2020-01-01"),
    by = "day",
    length.out = period
  ),
  Value = c(
    cumsum(rnorm(period)),
    cumsum(rnorm(period)),
    cumsum(rnorm(period))
  ),
  Type = c(
    rep("a", period),
    rep("b", period),
    rep("c", period)
  )
)

ggplot(df) +
  geom_line(aes(Date, Value, colour = Type)) +
  gghighlight(min(Value) < -15) # highlight the group if its min value is below -15

Key features

→ Highlight a histogram with multiple groups

Use a facetted version with facet_wrap(~ Species) and the gghighlight feature allow us to showcase distribution of each group while maintaining the background distributions for other variables.

Example:

library(ggplot2)
library(gghighlight)

# load the iris dataset
data(iris)

# show distribution of Sepal.Length of each species
ggplot(iris, aes(Sepal.Length, fill = Species)) +
  geom_histogram() +
  gghighlight() +
  facet_wrap(~Species)

→ Highlight points in a scatter plot

You can highlight specific points by indicating the properties of the points in question.

Example:

library(ggplot2)
library(gghighlight)

# create dataset
set.seed(1)
df_scatter <- data.frame(
  xvalue = rnorm(n = 100),
  yvalue = rnorm(n = 100)
)

# show distribution of Sepal.Length of each species
ggplot(df_scatter, aes(xvalue, yvalue)) +
  geom_point() +
  gghighlight(yvalue > 1.5, xvalue < 1)

→ Specify properties of unhighlighted

You can define the style of elements outside your filters using the unhighlighted_params argument.

Example:

library(ggplot2)
library(gghighlight)

ggplot(df) +
  geom_line(aes(Date, Value, colour = Type)) +
  gghighlight(min(Value) < -15,
    unhighlighted_params = list(
      linewidth = 0.3,
      colour = alpha("lightblue", 0.8)
    )
  )