More shiny

Grayson White

Math 241
Week 6 | Spring 2026

Week 6 Goals

Mon Lecture

• Introduction to shiny applications
• Get Project 1 group assignments

Wed Lecture

• shiny dashboards with Quarto
• Get all the details about Project 1

Annoucements

• DataFest 2026 @ Willamette
  • Great opportunity to meet folks and show off your data science skills!

• Updated Instructions for turning in Problem Set 4
  • Turn in the PDF on Gradescope as per usual
    • You may need to set #| eval: false in the chunks that have leaflet maps
  • Also Render your document to HTML (with #| eval: true for the leaflet map chunks)
  • Push the .qmd and .html to GitHub so the graders can grade your leaflet maps and interact with them easily

Recap

• Inputs: What user manipulates
  • Text
  • Sliders
  • Dropdown menus
  • Action buttons

• Output: What changes based on user’s selections
  • Graphs
  • Maps
  • Tables
  • Text

• Use reactive programming
  • Update outputs when inputs change

shiny Recap – Main Components

• UI: User interface
  • Defines how your app looks

• Server function
  • Defines how your app works

library(shiny)

# User interface
ui <- fluidPage()

# Server function
server <- function(input, output){}

# Creates app
shinyApp(ui = ui, server = server)

Building Outputs

Server-side:

• Save the object with output$___.

• Use a render___({}) function to create the object.

  • Look at cheatsheet for examples.

• Access inputs with input$___.

UI-side:

• Place output with ___Output().

Troubleshooting common issues:

• Must comma separate all the elements in the ui.
• But don’t add a comma after the last element in the ui.

More Reactivity: observe()

• Let’s look at another app in the learn-shiny repo.

  • Within the ShinyApps folder, it is in “app_biketown”.

• Features leaflet functions and observe().

• Need to use leafletProxy() so that the entire map isn’t redrawn with each update to the inputs.

Adding Source Code to the Dashboard

Create a DESCRIPTION text file with this text:

Title: Math 241 Names

Author: Grayson White

AuthorUrl: https://graysonwhite.shinyapps.io/my_first_app/

DisplayMode: Showcase

Type: Shiny

Uploading to ShinyApps.io

• Go to https://www.shinyapps.io/
• Create an account or sign in via your GitHub username.

• Install rsconnect.

install.packages('rsconnect')

library(rsconnect)

• Configure rsconnect.

setAccountInfo(name="<ACCOUNT>", token="<TOKEN>", secret="<SECRET>")

• Deploy app. (This will take a couple minutes.)

# Include correct file path
deployApp("ShinyApps/biketown")

Quarto-based shiny dashboards

• Will allow you to create dashboards that harness the power of shiny but also the simplicity of Quarto.

• Can also been used to create stand-alone HTML files with some interactivity.

• I converted the Shiny App we created last time into a Quarto shiny dashboard.

  • Let’s focus on some of the changes.

So Much More…

• There are lots of potential widgets to consider including for inputs.

• My apps were ugly. Start with ugly apps but then make them pretty!

  • Pick a better theme: Quarto dashboard themes and shiny themes.
  • Use appropriate labels and titles.
  • Try out several different layouts: Quarto dashboard layouts and shiny layouts.
  • Consider adding HTML to further customize the appearance of the UI.

With that in mind…

Project 1

Big idea:

• Create an interactive web application/dashboard using shiny or Quarto shiny dashboards.

• Make sure to satisfy the requirements (given in the handout).

• But then stretch yourself to add new features and a “non-default” look to your app.

  • Create something you’d want to share in a data science portfolio.

• Will have opportunities for feedback from your peers and from me as you are iterating toward the final product!

• Also as part of the project, each group member will write a “data scientist’s statement” and reflect on the goals and design choices of the dashboard.

Practice

Grab appPractice.qmd from the “learn-shiny” Github repo.

Next Week

• Learn even more about data types in R (strings / dates / factors)
• Learn to match strings with regular expressions