13 Shiny

Lets you present tables and charts that will react to inputs.

13.1 Basic Shiny Structure

library(shiny)

ui <- fluidPage(
        titlePanel("Hello Shiny!")
      )

server <- function(input, output) {
}

shinyApp(ui, server)

13.2 User Interface

13.2.1 Layout

Various layouts can be used however the most common is a fluid layout. The page can be divided into rows and columns. Fixed text and styling can also be added.

library(shiny)

ui <- fluidPage(
          fluidRow(
             column(width=4, "row1 column1", style = "background-color:red;"),
             column(width=4, "row1 column2", style = "background-color:orange;"),
             column(width=4, "row1 column3", style = "background-color:yellow;")
          ),  
          fluidRow(
             column(width=4, "row2 column1", style = "background-color:green;"),
             column(width=4, "row2 column2", style = "background-color:blue;"),
             column(width=4, "row2 column3", style = "background-color:purple;")
          )
      )

server <- function(input, output) {
}

shinyApp(ui, server)

13.2.2 Inputs

There are various Inputs that can be added to the UI. Behind the scenes these generate HTML code: * sliderInput() # Adds an input slider * fileInput() # Adds a file selector * textInput() # Adds a text input box * selectInput() # Adds a dropdown list * actionButton() # Adds an action button * dateRangeInput() # Adds a date selector The first argument of all the inputs/ouputs is a unique id.

ui <- fluidPage(
        fluidRow(
          column(width=4,
                 sliderInput("slider", "Generate n randoms", min = 0, max = 1000, value = 500, step = 100)
                 ),
          column(width=4,
                 fileInput("loadfile", "Choose file")),
          column(width=4,
                 selectInput("dropdown", "Select an option", c("Rare" = "1",
                                                               "Medium" = "2",
                                                               "Well Done" = "3")))
        )
)

server <- function(input, output) {
}

shinyApp(ui, server)

13.2.3 Outputs

There are various Outputs that can be added to the UI: * htmlOutput() # Adds space for text * tableOutput() # Adds space for a table * plotOutput() # Adds space for a chart

Nb. these will be empty until a function is added to the server that adds content.

ui <- fluidPage(
        fluidRow(
          htmlOutput("text1", width="75%", height="50px"),
          tableOutput("table1"),
          plotOutput("chart1", width="75%", height="100px")
        )  
)

server <- function(input, output) {
}

shinyApp(ui, server)

Other packages extend shiny ui outputs. * plotlyOutput # Adds space for a plotly chart [plotly] * ggiraphOutput # Adds space for a ggiraph chart [ggiraph] * DTOutput # Adds space for a data table [DT]

13.3 Server

UI inputs and outputs wont work unless they link to a server process/function.

13.3.1 Linking to UI outputs

• renderPlot() # creates reactive ggplot output
• renderText() # creates reactive tetx output
• renderTable() # creates reactive table output
• renderDataTable() # creates reactive DT output The UI output id and the server output name must match.

ui <- fluidPage(
        fluidRow(
          plotOutput("chart1")
        )  
)

server <- function(input, output) {
  # This output links to the ui plotOutput via the id "chart1"
  output$chart1 <- renderPlot({
    plot(mtcars$wt, mtcars$mpg)
  })
}

shinyApp(ui, server)

Other packages extend shiny server outputs. * renderPlotly # creates reactive plotly chart [plotly] * renderggiraph # creates reactive ggiraph chart [ggiraph]

13.3.2 Linking to UI inputs

The UI input id and the server input name must match.

ui <- fluidPage(
  fluidRow(
    selectInput("dropdown", "Select an option", c("Weight" = "wt",
                                                  "Horespower" = "hp",
                                                  "Cylinders" = "cyl"))
  ),
  fluidRow(
    plotOutput("chart1")
  ) 
)

server <- function(input, output) {
  # This output links to the ui plotOutput via the id "chart1"
  output$chart1 <- renderPlot({
    plot(mtcars[[input$dropdown]], mtcars$mpg)
  })
}

shinyApp(ui, server)

13.4 Shiny Dashboard

Provides a dashboard template for Shiny Apps.

library(shiny) library(shinydashboard)