STAT3622 Data Visualization (Lecture 7)

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# STAT3622 Data Visualization (Lecture 7)
## Shiny iDataViz Web Apps
### <br>Dr. Aijun Zhang<br> The University of Hong Kong
### 24 March 2020

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# What's covered in this lecture?

- Introduction to Shiny 
  
  - Shiny App Structure
  
  - R Markdown with Shiny
  
  - UI Widgets

- Shiny Dashboard

- Shiny App Examples in RStuido/Rmarkdown

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# 1. Introduction to Shiny

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# Introduction to Shiny

- Shiny is an R package, for easy building interactive web apps straight from R.

- Linked views of interactive data visualization (compare with plotly)

- It may enable R Markdown (dynamic documents) to be interactive

- It provides tools for building dashboards …

- Click [here](https://shiny.rstudio.com/images/shiny-cheatsheet.pdf) to download the Shiny cheat sheet.

- Click https://shiny.rstudio.com/tutorial/ for wonderful tutorials

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# Basic Structure: app.R

```r
library(shiny)
ui <- ...
server <- ...
shinyApp(ui = ui, server = server)
```

- **ui module** (in the front end): control widgets (HTML elements)

- **server module** (in the back end): DataViz logic (i.e. R codes)

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# R Markdown with Shiny

- In Rmd, add "runtime: shiny" in the header

- R chunk with `shinyApp(ui=..., server=...)`

```r
shinyApp(
  # Define UI elements in the front end
  ui = fluidPage(
    titlePanel("Whatever App Title"),
    sidebarPanel(sliderInput("nbreaks", "Number of breaks:",
                             min = 6, max = 50, value = 20)),
    mainPanel(plotOutput("thisPlot"))
    ),
  # Define server logic in the back end
  server = function(input, output) {
    output$thisPlot <- renderPlot({
      hist(iris$Sepal.Length, n=input$nbreaks)
      })
  }, 
  options = list(height = 500)
)
```

- "Run Document" to generate the report with live Shiny apps

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# Shiny makes interactive graphics!

- Run the previous code in ["app.R"]() or in R markdown to have the following output:

- Unfortunately, so far the Rmd:xaringan (format for this presentation) does not support Shiny yet.

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# UI Widgets

- Web/HTML elements (See the collections below). Shiny has a built-in family of functions to create these widgets. See RStudio-Shiny's [Lesson 3](https://shiny.rstudio.com/tutorial/written-tutorial/lesson3/).

- Each widget is associated with an ID/pointer (invisible) and a label (visible).

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# Built in Examples

In R console, run the following launch Shiny built-in examples

```r
library(shiny)
runExample("01_hello")
runExample("02_text")
runExample("03_reactivity")
runExample("04_mpg")
runExample("05_sliders")
runExample("06_tabsets")
runExample("07_widgets")
runExample("08_html")
runExample("09_upload")
runExample("10_download")
runExample("11_timer")
```

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# Shiny Dashboard

- **R:shinydashboard** with URL: http://rstudio.github.io/shinydashboard/index.html

- Get started from here: http://rstudio.github.io/shinydashboard/get_started.html

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# 2. Shiny App Examples

<br>

## Switch to RStudio and RMarkdown

Download [Lecture7_Shiny.Rmd](./Lecture7_Shiny.Rmd) with Runtime support.

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# Thank you!

Q&A or Email ajzhang@umich.edu。