Widgets!

Outline

Shiny Review

Widgets

Plotly + Shiny

Multiple tabs

{review}

shinyapps.io

Browser passes information back to R

A free cloud-based server that passes information between an RStudio session and a browser

Shiny server builds a web page based on R output

all of this happens on a server somewhere else

{sign up for an account}

{widgets!}

Widgets

Set of elements a user interacts with

Sends values to server.R file as input$value

Facilitates interactivity!

Widgets: textInput

ui.R

server.R

shinyUI(fluidPage(
    
  # Create a text input element
  textInput("text", label = h3("Text input"), value = "Enter ..."),
    
  # Show output$userText from server.R
  textOutput('userText')
      
))
### Use input to create a string    
shinyServer(function(input, output) {
  
  # Render some text, using the value from the ui
  output$userText <- renderText({
      return(paste0('The user typed: ', input$text))
  })
  
})

Widgets: radioInput

ui.R

server.R

shinyUI(fluidPage(
  
  # Radio buttons
  radioButtons("color", label = "Color",
               choices = list("Green" = 'green', "Blue" = 'blue'), 
               selected = 'green'),
  plotOutput('histogram')
))
### Use input to create a histogram    
shinyServer(function(input, output) {
  
  # Reder a histogram of a given color
  output$histogram <- renderPlot({
    x <- rnorm(1000)
    return(hist(x, col = input$color))
  })
})

{example-2}

{plotly}

Plotly

Plays pretty nicely with Shiny

Minor adjustments needed:

## ui.R
shinyUI(fluidPage(
  mainPanel(
    plotlyOutput('scatter'), 
    plotlyOutput('map')
  )
))
## server.R
shinyServer(function(input, output) { 
  
  # Render a plotly object
  output$map <- renderPlotly({ 
    build_map(data, input$export)  
  })
})

Strings as variable names

......WHY?!?!?!!?.....

Select variables to show using Shiny widgets

Easy doable 

life_expectancy <- c(75, 73, 71)
var_to_graph <- 'life_expectancy'
# Parse and evaluate var_to_graph
eval(parse(text = var_to_graph))
[1] 75, 73, 71

{exercise-1}

Panel Layout

shinyUI(fluidPage(
  # Main title panel
  titlePanel("title panel"),

  # Declare a sidebar layout
  sidebarLayout(
    
    # Put sidebar elements in here (i.e., widgets)
    sidebarPanel( "sidebar panel"),
    
    # Put main stuff in here (i.e., plots)
    mainPanel("main panel")
  )
))

{example 3}

TabPanel

# Define UI for random distribution application 
shinyUI(fluidPage(
    
  # Application title
  titlePanel("Tabsets"),
  
  # Sidebar with controls to select the random distribution type
  sidebarLayout(
    sidebarPanel(
      ....
    ),
    
    # Create tabs by passing in label and content
    mainPanel(
      tabsetPanel(type = "tabs", 
        tabPanel("Plot", plotOutput("plot")), 
        tabPanel("Summary", textOutput("summary")), 
        tabPanel("Table", tableOutput("table"))
      )
    )
  )
))

NavBar

# Create UI of a Navbar page
shinyUI(navbarPage('Page Title',
                   
  # Create different pages using tabs
  tabPanel('Nav. Label 1',
    titlePanel('Page 1 title'),
    
    # Controls
    sidebarLayout(
      sidebarPanel(  
       #widgets
      ),        
      # Render plot
      mainPanel(
        plotlyOutput("myChart")
      )
    )
  ), 

  # Create your second tab (page)
  tabPanel('Nav. Label 2',
    titlePanel('Page 2 title'),
    # Other contents of page 2 ...
  )
))

{exercise-2}

Resources

Assignments

Assignment-8: building applications (due Wed. 3/2)

Keep working on your final projects!

shiny-widgets

By Michael Freeman

shiny-widgets

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