Highlight geoms in ggplot2.

## Installation

install.packages("gghighlight")

# Or the development version from GitHub:
# install.packages("devtools")
devtools::install_github("yutannihilation/gghighlight")

## Example

Suppose we have a data that has so many series that it is hard to identify them by their colours as the differences are so subtle.

library(ggplot2)

ggplot(d) +
geom_line(aes(idx, value, colour = type))

With gghighlight(), we can highlight the lines whose max values are larger than 20:

library(gghighlight)

p <- ggplot(d) +
geom_line(aes(idx, value, colour = type)) +
gghighlight(max(value) > 19)
#> label_key: type

p

The result is an usual ggplot object, so it is fully customizable. For example, it can be used with custom themes and facets.

p + theme_minimal()


p + theme_minimal() + facet_wrap(~ type)

gghighlight() can highlight almost any geoms. For more details, please read Introduction to gghighlight.