A custom ggplot2 theme for Cornell

Application exercise

February 20, 2024

Install the required font files first!

Run _install-spectral.sh from the terminal first before attempting to complete the AE. You need to install the Spectral font files to ensure the fonts are correctly rendered in the charts. After running this shell script, restart your R session and it should then be available for use.

Cornell University brand identity

Organizational branding is a set of visual and verbal elements that represent an organization. It is “how your audience perceives you” and created through “many elements, including your name, logo, tagline, website, colors, collateral, messaging, positioning, graphic elements, social media, and other outreach platforms.”1

Cornell University maintains detailed guidelines for its brand identity. The design center provides explicit instructions for using the Cornell logo, color palette, and typography, as well as downloadable materials such as a PowerPoint template.

Suppose we wish to create a series of statistical charts to be used in a Cornell Bowers CIS2 presentation, but we want to ensure they are both reproducible as well as consistent with the university’s branding. We can use the ggplot2 package to create a custom theme that adheres to the Cornell brand identity.

Basic bar chart

Let’s create a basic chart to assist us with generating an appropriate ggplot2 theme. Here we will use graduation trends from Cornell University from College Scorecard. In this instance, we will use a bar chart to visualize the percentage of degrees awarded for three fields of study from 2017-21.

cornell_degrees <- read_csv("data/cornell-degrees.csv")
# A tibble: 105 × 3
   field_of_study  year    pct
   <chr>          <dbl>  <dbl>
 1 Computer        2001 0.0859
 2 Computer        2002 0.0745
 3 Computer        2003 0.0463
 4 Computer        2004 0.0327
 5 Computer        2005 0.032 
 6 Computer        2006 0.0221
 7 Computer        2007 0.0263
 8 Computer        2008 0.0262
 9 Computer        2009 0.0264
10 Computer        2010 0.0297
# ℹ 95 more rows
cornell_degrees_plot <- cornell_degrees |>
  filter(year >= 2017) |>
  # prep data for specific bar plot
    year = factor(year),
    field_of_study = fct_reorder2(.f = field_of_study, .x = year, .y = pct)
  ) |>
  ggplot(mapping = aes(x = field_of_study, y = pct, fill = year)) +
  # ensure padding between dodged bar segments
  geom_col(position = position_dodge2(padding = 0.2)) +
  scale_x_discrete(labels = label_wrap(width = 15)) +
  # format y axis labels
  scale_y_continuous(labels = label_percent()) +
  # optimal labels for chart
    title = "Computer degrees have surpassed Engineering at Cornell",
    subtitle = "Percentage of degrees awarded by field of study",
    x = NULL,
    y = NULL,
    fill = NULL,
    caption = "Source: College Scorecard"

Develop a custom Cornell theme for ggplot2

Based on Cornell’s brand identity, we want to ensure our theme adheres to the following requirements:

In addition, we want to

Note this final requirement is not part of the theme() as defined by ggplot2, but requires us to modify the appropriate scale for the chart.

Your turn: Implement a Cornell-branded theme for ggplot2 that meets the requirements outlined above.


Replace the TODO placeholders with the appropriate values. Use the ggplot2 theme() documentation as a reference.

# cornell color palette - accent colors
cornell_pal <- c("#006699", "#6EB43F", "#F8981D", "#EF4035", "#073949")

cornell_degrees_plot +
  # change color palette
  scale_fill_TODO(values = cornell_pal) +
  # use theme_minimal() as a starting point
    base_family = "TODO",
    base_size = TODO
  ) +
    plot.title.position = "TODO",
    plot.title = element_text(hjust = TODO),
    plot.subtitle = element_text(hjust = TODO),
    legend.position = "TODO",
    panel.grid.major.x = TODO,
    panel.grid.minor.x = TODO,
    panel.grid.major.y = element_line(TODO),
    panel.grid.minor.y = element_line(TODO),
    axis.text = element_text(TODO),
    legend.text = element_text(TODO)
Error in scale_fill_TODO(values = cornell_pal): could not find function "scale_fill_TODO"

Turn into a reusable function

Demo: Convert your Cornell theme into a reusable theme_cornell() function and test it on two different charts.

# define theme as its own function
theme_cornell <- function(
    ) {
# existing bar chart
cornell_degrees_plot +
  scale_fill_TODO(values = cornell_pal) +
Error in scale_fill_TODO(values = cornell_pal): could not find function "scale_fill_TODO"
# line graph
cornell_degrees |>
    field_of_study = fct_reorder2(.f = field_of_study, .x = year, .y = pct)
  ) |>
  ggplot(aes(x = year, y = pct, color = field_of_study)) +
  geom_point() +
  geom_line() +
  scale_x_continuous(limits = c(2000, 2021), breaks = seq(2000, 2020, 4)) +
  scale_color_TODO(values = cornell_pal) +
  scale_y_continuous(labels = label_percent()) +
    x = "Graduation year",
    y = "Percent of degrees awarded",
    color = "Field of study",
    title = "Cornell University degrees awarded from 2001-2021",
    subtitle = "Only the top five fields as of 2021",
    caption = "Source: College Scorecard"
  ) +
  # use the Cornell theme
Error in scale_color_TODO(values = cornell_pal): could not find function "scale_color_TODO"


  1. Source: What is Organizational Branding?↩︎

  2. According to the Cornell Bowers CIS brand guidelines, always refer to it as Cornell Bowers CIS or the more formal Cornell Ann S. Bowers College of Computing and Information Science or Cornell Bowers Computing and Information Science, never just CIS.↩︎