plot2

A lightweight extension of the base R graphics system, with support for automatic grouping, legends, facets and various other enhancements.

Installation

plot2 is not yet on CRAN, but can be installed from R-universe.

install.packages("plot2", repos = "https://grantmcdermott.r-universe.dev")

Our goal is to submit to CRAN within the few months of 2024, once we have settled on some remaining design choices and features support. You can take a look at the open issues to see what’s currently under consideration. Please feel free to weigh on these if you have opinions. We want end users to have a say in determining the final product.

Motivation

R users are spoiled for choice when it comes to visualization frameworks. The options of course include ggplot2 (arguably the most important graphics system of the last decade) and lattice, not to mention a bewildering array of extensions built around, on top of, and in between these amazing packages.

It is perhaps not surprising, then, that the base R graphics system sometimes gets short shrift. This is unfortunate, because base R offers very powerful and flexible plotting facilities. Just type demo(graphics) or demo(persp) into your R console to get an idea. Or, take a look at these two excellent tutorials. The downside of this power and flexibility is that base R plotting can require a fair bit of manual tinkering. A case in point is plotting grouped data with an appropriate legend. Doing so with the generic plot() function can require several function calls or a loop, fiddling with your plot regions, and then generating the legend manually.

The plot2 package aims to remove this overhead. It provides a lightweight extension of the base R plot system with various convenience features, particularly for creating (2D) scatter and line plots using grouped data. For example, the core plot2() function makes it easy to plot different categories of a dataset in a single function call and highlight these categories (groups) using modern colour palettes. Coincident with this grouping support, plot2() also produces automatic legends with scope for further customization. While the package offers several other enhancements, it tries as far as possible to be a drop-in replacement for the equivalent base plot function. Users should generally be able to swap a valid plot() call with plot2() without any changes to the expected output.

Examples

We provide a “Get Started” tutorial with numerous examples on the package homepage. But here are some quickstart examples of the package in action.

library(plot2)

# Grouped scatterplot with automatic legend

# Like plot(), we can use either an atomic or formula interface...

# with(iris, plot2(x = Petal.Length, y = Sepal.Length, by = Species)) # atomic
plot2(Sepal.Length ~ Petal.Length | Species, data = iris) # formula (same)

 
# Same plot with a few extra aesthetic tweaks

plot2(
  Sepal.Length ~ Petal.Length | Species, 
  data = iris,
  palette = "dark", pch  = 16,
  grid = TRUE, frame = FALSE
)

# Grouped density plot with automatic legend (and some aesthetic tweaks)

plot2(
  ~ Petal.Length | Species,
  data = iris,
  type = "density",
  palette = "dark", fill = "by",
  grid = TRUE,
  main = "Distribution of petal lengths by species"
)

# Facet plots are supported too (combined with "by" grouping, or on their own)

iris2 = transform(iris, Sepals = ifelse(Sepal.Length>6, "Long", "Short"))
plot2(
  Sepal.Length ~ Petal.Length | Sepals, data = iris2,
  facet = ~Species,
  facet.args = list(bg = "grey90"),
  palette = "classic",
  main = "Faceted Sepals!",
  grid = TRUE, frame = FALSE
)