Brief refresher of ggplot2 basics

What are some common ggplot2 issues?

What are some common ggplot2 issues?

What are some common ggplot2 issues?

Some small ggplot2 changes

• plot saving and sizing
• text sizing
• overlapping facet labels
• axis labels

Before we go any further!

Have you ever spent ages tinkering with a plot you’re previewing in RStudio…

Before we go any further!

…and then used ggsave() to save an image, and ended up with something like this:

Why does this happen?

• This happens because we preview the chart at 96dpi (low resolution) in RStudio, but save the chart at 300dpi (high resolution) using the defaults for ggsave().

• We could set ggsave(dpi = 96) but we usually don’t want to save a low resolution image.

• Instead we want to preview the chart in RStudio at the higher resolution we’ll be saving it at.

How do we fix this?

Live demo

Dealing with text

Some common problems:

• theme text
  • Many elements of to set the text size of
  • Resizing chart means redefining text sizes
• geom text
  • Scales differently from theme sizes
• axis text
  • Long (ugly labels)
  • Overlapping labels

Live demo

Exercise 1

ggplot(
  data = plot_data,
  mapping = aes(x = year, y = value, colour = country_name)
) +
  geom_line()

ggplot2 extensions

Dealing with loooooooooooooooooooong text

Dealing with loooooooooooooooooooong text

Live demo

Annotations in R

There are many packages for working with annotations in ggplot2:

• ggplot2
• ggtext
• cowplot
• ggannotate
• ggrepel
• …

Placing annotations

• Where should the annotation go? -> ggannotate
• Single facet annotations -> ggh4x
• Wrap long annotation text -> ggtext
• Annotations outside panel -> cowplot
• Many overlapping annotations -> ggrepel

Tip: use glue to create data-driven annotations

Live demo

Exercise 2

• Use either ggtext or marquee to ensure the subtitle text wraps onto multiple lines.
• Use either ggtext or marquee to make sure country names are all visible in the facet labels.
• Add an annotation to the "Australia" facet.

Use variables

Create variable for colours:

text_col <- "grey10"
highlight_col <- "#B01D5F"
bg_col <- "white"

Custom themes

Remembering all of the theme elements is tricky

• Step 1: Parameterise your theme elements
• Step 2: Make your own reusable function by adapting an existing theme
• Step 3: Put your function in a package (optional)
• Step 4: Set up reusable templates for new ggplot2 charts (optional)

Template files

Create a template file (inside or outside of a package) that contains the theme() defaults you want to use.

# Load packages -----------------------------------------------------------

library(tidyverse)
library(showtext)
library(ggtext)
library(glue)
library(ggview)


# Load data ---------------------------------------------------------------



# Load fonts --------------------------------------------------------------

font_add_google("Oswald")
font_add_google("Nunito")
showtext_auto()
showtext_opts(dpi = 300)
title_font <- "Oswald"
body_font <- "Nunito"


# Define colours and fonts-------------------------------------------------

bg_col <- "#F2F4F8"
text_col <- "#151C28"
highlight_col <- "#7F055F"


# Data wrangling ----------------------------------------------------------


# Define text -------------------------------------------------------------

title <- ""
st <- ""
cap <- ""


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

theme_minimal(base_size = 10, base_family = body_font) +
  theme(
    plot.margin = margin(5, 5, 5, 5),
    plot.title.position = "plot",
    plot.caption.position = "plot",
    plot.background = element_rect(fill = bg_col, colour = bg_col),
    panel.background = element_rect(fill = bg_col, colour = bg_col),
    plot.title = element_textbox_simple(
      colour = text_col,
      hjust = 0,
      halign = 0,
      margin = margin(b = 5, t = 5),
      family = title_font,
      face = "bold",
      size = rel(1.5)
    ),
    plot.subtitle = element_textbox_simple(
      colour = text_col,
      hjust = 0,
      halign = 0,
      margin = margin(b = 5, t = 5),
      family = body_font
    ),
    plot.caption = element_textbox_simple(
      colour = text_col,
      hjust = 0,
      halign = 0,
      margin = margin(b = 0, t = 10),
      family = body_font
    ),
    strip.text = element_textbox_simple(
      face = "bold",
      margin = margin(t = 10),
      size = rel(0.9)
    ),
    panel.grid.minor = element_blank()
  ) +
  canvas(
    width = 7, height = 5,
    units = "in", bg = bg_col,
    dpi = 300
  ) # -> p


# Save --------------------------------------------------------------------

save_ggplot(
  plot = p,
  file = "image.png"
)

Live demo

Exercise 3

• Creating your own theme() function
  • Use ggtext and marquee to auto-wrap text
  • Set facet height
  • Apply desired styling

Resources