In stephlocke/Rtraining: Training Materials on R

Objective

Learn what the heck shiny is and how you use it!

Logistics

• Approx 55 mins talk + 20 mins adventure (liberally sprinkled)
• Links going out during talk on twitter (@SteffLocke)
• Ask your questions throughout
• I'll do some whistlestop R but see my Intro to R or for more in-depth my SQLSaturday pre-con
• Please give feedback & thanks to the organisers of @SQLBits

FundaRmentals

# variable assignment
a <- 1
a
# functions
paste0(c("SQL","Super"),c("Bits","Heroes"))

What's Shiny?

• An interactive report framework
• An R package that is available free (as is the server edition)
• Uses "modern web standards" like bootstrap under the hood

Quick example

library(data.table)
library(shiny)
defaultdisplay<-list(
    width="100%", height="75%"
  )
shinyAppDir(
  system.file("examples/06_tabsets", package="shiny"),
  options = defaultdisplay
)

Shiny structure

Contents | Typical

A shiny application report consists of two functions:

• shinyServer()
• shinyUI()

One says what to execute and the other states how to present it. Do all data manipulation, chart production in shinyServer()

Contents | "Lite"

defaultdisplay<-list(width="100%", height="75%")

shinyApp(
    ui      = fluidPage(),
  , server  = function(input, output) {}
  , options = defaultdisplay
)

Files

You typically split into two files:

• server.R containing shinyServer()
• ui.R containing shinyUI()

This can then be run with runApp()

You can do a single file example app.R which contains both functions but this is typically better for very short apps.

Front-end layout

Use these just inside shinyUI() to produce a layout

lsp <- function(package, all.names = FALSE, pattern) 
{
  package <- deparse(substitute(package))
  ls(
      pos = paste("package", package, sep = ":"), 
      all.names = all.names, 
      pattern = pattern
  )
}
data.table(`Page Types`=lsp(shiny,pattern = "Page"))

Typical Inputs

Dates

shinyApp(
  ui = fluidPage(dateInput("datePicker", "Pick a date:", 
                           format="dd/mm/yy"),
                 dateRangeInput("dateRange", "Pick dates:", 
                                start=Sys.Date(), 
                                end=Sys.Date() ) ),
  server = function(input, output) {}
  ,options = defaultdisplay
)

Values | Simple

shinyApp(
  ui = fluidPage(numericInput("vals", "Insert a number:", 
                              value=15, min=10)  ),
  server = function(input, output) {}
  ,options = defaultdisplay
)

Values | Sliders

shinyApp(
  ui = fluidPage(sliderInput("vals", "Insert a number:", 
                             min=0, max=50, value=15)  ),
  server = function(input, output) {}
  ,options = defaultdisplay
)

Text | Single line

shinyApp(
  ui = fluidPage(textInput("char", "Insert text:")  ),
  server = function(input, output) {}
  ,options = defaultdisplay
)

Text | Paragraph

shinyApp(
  ui = fluidPage(tags$textarea(id="charbox", rows=3, 
                               cols=40, "Default value")  ),
  server = function(input, output) {}
  ,options = defaultdisplay
)

Selectors

shinyApp(
  ui = fluidPage(selectInput("multiselect", "Pick favourites:",
                             c("Green","Red","Blue"),
                             multiple=TRUE)  ),
  server = function(input, output) {}
  ,options = defaultdisplay
)

List of input types

data.table(`Input controls`=lsp(shiny,pattern = "Input"))

Typical Outputs

Input values

shinyApp(
  ui = fluidPage(textInput("char", "Insert text:") ,
                 textOutput("text")  ),
  server = function(input, output) {
    output$text <- renderText(input$char)
  }  ,options = defaultdisplay
)

Basic tables

shinyApp(
  ui = fluidPage(tableOutput("basictable")  ),
  server = function(input, output) {
    output$basictable <- renderTable(head(iris,5))
  }  ,options = defaultdisplay
)

Interactive tables

shinyApp(
  ui = fluidPage(dataTableOutput("datatable")  ),
  server = function(input, output) {
    output$datatable <- renderDataTable(head(iris,5))
  }  ,options = defaultdisplay
)

Charts

shinyApp(
  ui = fluidPage(plotOutput("chart")  ),
  server = function(input, output) {
    output$chart <- renderPlot(pairs(iris))
  }  ,options = defaultdisplay
)

Reactivity | Not covered in-depth

Simple reactivity

• Make functions that process inputs only when they change

a <- reactive({input$a})
a

• Use these reactive functions in downstream server items for DRY & to reduce processing effort

An Example

shinyApp(
  ui = fluidPage(textInput("char", "Insert text:") ,
                 textOutput("textA"),textOutput("textB") ),
  server = function(input, output) {
    char<-reactive({rep(input$char,5)})
    output$textA <- renderText(paste(char(),collapse="+"))
    output$textB <- renderText(paste(char(),collapse="-"))
  }
  ,options = defaultdisplay
)

Styling

shinythemes

• Get a different look and feel with the package shinythemes
• Uses a number of bootstrap based themes
• Good-looking quickly, but of course not company branded
• View themes at bootswatch.com

CSS

• Shiny outputs html so you can write CSS that works with it
• Full list of CSS items doesn't exist, use F12 on chrome or check out selectorgadget via rvest
• Simple stuff like body, h1 will all work

shinydashboards

• Makers of shiny working on a framework: Shiny Dashboard
• A new dashboarding framework - still immature but useful
• Excellent walkthrough on Data Driven Security

Infrastructure

Ad-hoc shiny

• Rstudio (easiest) or just run directly
• Use shiny::runApp()
• Great for "expert" use

Cloud

• shinyApps.io
• Deploy with shinyApps package
• Free for light use
• Extra management features at increased costs
• Great for hands-off management

Central server

• shiny-server
• Runs on linux
• Free community edition
• Extra management features & LDAP auth in Pro Edition (but can roll your own)
• Great for sensitive and/or db-driven appplications

Let's put it all together!

Q & A

Recommended reading

• Shiny site
• A bit outdated but: Web Application Development with R Using Shiny
• Reactivity Overview
• shiny for teaching maths
• Show me Shiny!
• Deploying shiny apps

The end!

stephlocke/Rtraining documentation built on May 30, 2019, 3:36 p.m.