Introduction to RShiny

class: center, middle, inverse, title-slide

.title[
# Introduction to RShiny
]
.author[
### Justin Post
]

---

layout: true

---

# What do we want to be able to do?

Data Science!

- Read in raw data and manipulate it
- Combine data sources
- Summarize data to glean insights
- Apply common analysis methods
- Communicate Effectively

Important considerations for data analysis workflow:

- **Reproducibility**  
- **Version control**  
- **Collaboration**

---

# What is R Shiny?

- [R Shiny Package](https://shiny.posit.co/)

+ Developed by RStudio  
    + Allows for creation of apps and dashboards  
  
- Usually a .R file (or two) with special code to create an app  
  
    + `ui.R` (User Interface)  
    + `server.R` (R functions that run/respond to UI)
    + `app.R` (both UI and server combined)

---

# Example App

[Example App](https://shiny.stat.ncsu.edu/jbpost2/BasicApp/)

```r
library(...)
ui <- fluidPage(
  # Application title
  titlePanel("Investigation of Mammal Sleep Data"),
  # Sidebar with options for the data set
  sidebarLayout(
    sidebarPanel(
      h3("Select the mammal's biological order:"),
      selectizeInput("vore", 
                     "Vore", 
                     selected = "omni", 
                     choices = levels(as.factor(msleep$vore))
                     ),
     ...
    # Show outputs
    mainPanel(
      plotOutput("sleepPlot"),
      textOutput("info"),
      tableOutput("table")
      )
  )
)
```

---

# Example App

[Example App](https://shiny.stat.ncsu.edu/jbpost2/BasicApp/)

```r
server <- function(input, output, session) {
  #get data for only order specified
  getData <- reactive({
    vores <- input$vore
    msleep %>% filter(vore == vores)
  })
  #create plot
  output$sleepPlot <- renderPlot({
    #get data
    sleepData <- getData()
    #base plotting object
    g <- ggplot(sleepData, aes(x = bodywt, y = sleep_total))
    if (input$conservation) {
      g + geom_point(size = input$size, aes(col = conservation))
    } else {
      g + geom_point(size = input$size)
    }
  })
  ...
```

---

# Example App

[Example App](https://shiny.stat.ncsu.edu/jbpost2/BasicApp/)

- This code goes below the `ui` and `server` objects

```r
# Run the application 
shinyApp(ui = ui, server = server)
```

- Save file as `app.R` and RStudio knows it is a shiny app!
- Let's create this app!

---

# How to Learn about Shiny?

- Learn about user interface (UI) elements

+ UI layout
    + Input widgets (sliders, numeric inputs, etc.)
    + Formatting of text/HTML elements
    + Outputs from server

- Understand how the server (R) back-end works with the UI elements

+ Reactivity concepts
    + Accessing UI inputs
    + Creating outputs

---

# Create your first apps!

- Read through the following pages of the Posit tutorial (**complete the `Your Turn` sections within these lessons** - no need to turn anything in, this is just to help you learn!)

- [Welcome to Shiny](https://shiny.posit.co/r/getstarted/shiny-basics/lesson1/)
    - [Build a user interface](https://shiny.posit.co/r/getstarted/shiny-basics/lesson2/)
        + Note: You will need to install (and load in your script) the `bslib` library. They use `page_sidebar()`, `cards()`, and `value_box()` from this package to build their UI
        
    - [Add Control Widgets](https://shiny.posit.co/r/getstarted/shiny-basics/lesson3/)