class: center, middle, inverse, title-slide # R Shiny - Part II ## Workshop on Plotting in R ###
Lokesh Mano
• 18-Jan-2022 ### NBIS, SciLifeLab --- exclude: true count: false <link href="https://fonts.googleapis.com/css?family=Roboto|Source+Sans+Pro:300,400,600|Ubuntu+Mono&subset=latin-ext" rel="stylesheet"> <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.3.1/css/all.css" integrity="sha384-mzrmE5qonljUremFsqc01SB46JvROS7bZs3IO2EmfFsd15uHvIt+Y8vEf7N7fWAU" crossorigin="anonymous"> <!-- ------------ Only edit title, subtitle & author above this ------------ --> --- name: content class: spaced ## Contents * [Reactivity](#react) * [Isolate reactivity](#isolate) * [observeEvent()](#observe) * [Updating Widgets](#updating) * [Error Validation](#error) * [Download Button](#download) * [Modularizing reactivity](#module) --- name: react ## Reactivity .size-95[ <img src="assets/images/react-code1.png" alt="drawing" width="800"/> ] --- name: react1 ## Reactivity .size-95[ <img src="assets/images/react-code2.png" alt="drawing" width="800"/> ] --- name: react2 ## Reactivity .size-95[ <img src="assets/images/react-code3.png" alt="drawing" width="800"/> ] --- name: react3 ## Reactivity .size-95[ <img src="assets/images/react-code4.png" alt="drawing" width="800"/> ] --- name: react4 ## Reactivity .size-95[ <img src="assets/images/react5.png" alt="drawing" width="800"/> ] --- name: react5 ## Reactivity .size-95[ <img src="assets/images/react6.png" alt="drawing" width="800"/> ] --- name: isolate ## Isolate reactivity * Reactivity can be controlled. -- * You will notice that as soon as you try to change the title, the histogram will update with new values .size-95[ <img src="assets/images/isolate1.png" alt="drawing" width="800"/> ] --- name: isolate2 ## Isolate reactivity .size-95[ <img src="assets/images/isolate2.png" alt="drawing" width="800"/> ] --- name: isolate3 ## Isolate reactivity .size-95[ <img src="assets/images/isolate3.png" alt="drawing" width="800"/> ] --- name:isolate4 ## Isolate reactivity .size-95[ <img src="assets/images/isolate4.png" alt="drawing" width="800"/> ] --- name:observe ## observeEvent() .size-95[ <img src="assets/images/observe.png" alt="drawing" width="500"/> ] --- name: updating ## Updating widgets * Widgets can be updated once initialised. * Add third argument **session** to server function ``` server=function(input,output,session) {} ``` -- * Example of a typical UI ``` ui=fluidPage( selectInput("select-input",label="selectInput",choices=c("A","B","C")), numericInput("numeric-input",label="numericInput",value=5,min=1,max=10), sliderInput("slider-input",label="sliderInput",value=5,min=1,max=10), ) ``` -- * Update functions can be used to update input widgets * Reactive observer `observe({})` monitors for a conditional change ``` server=function(input,output,session) { observe({ if(something) { updateSelectInput(session,"select-input",label="selectInput",choices=c("D","E","F")) updateNumericInput(session,"numeric-input",label="numericInput",value=10,min=1,max=10) updateSliderInput(session,"slider-input",label="sliderInput",value=8,min=1,max=10) } }) } ``` --- name: error ## Error validation * Shiny returns an error with missing or incorrect values .pull-left-70[.limity100[ ```r shinyApp( ui=fluidPage( selectInput("data_input",label="Select data", choices=c("","mtcars","faithful","iris")), tableOutput("table_output") ), server=function(input, output) { getdata <- reactive({ get(input$data_input,'package:datasets') }) output$table_output <- renderTable({head(getdata())}) }) ``` ]] .pull-right-30[ ![](assets/images/val1.png) ] -- * Errors can be handled in a controlled manner -- * `validate()` can be used to check input * `validate()` using `need()` .pull-left-70[.limity100[ ``` shinyApp( ui=fluidPage( selectInput("data_input",label="Select data", choices=c("","mtcars","faithful","iris")), tableOutput("table_output") ), server=function(input, output) { getdata <- reactive({ validate(need(try(input$data_input),"Please select a data set")) get(input$data_input,'package:datasets') }) output$table_output <- renderTable({head(getdata())}) }) ``` ]] .pull-right-30[ ![](assets/images/val2.png) ] -- * `validate()` using custom function .pull-left-70[.limity100[ ``` valfn <- function(x) if(is.null(x) | is.na(x) | x=="") return("Input data is incorrect.") shinyApp( ui=fluidPage( selectInput("data_input",label="Select data", choices=c("","mtcars","faithful","iris")), tableOutput("table_output") ), server=function(input,output) { getdata <- reactive({ validate(valfn(try(input$data_input))) get(input$data_input,'package:datasets') }) output$table_output <- renderTable({head(getdata())}) }) ``` ]] .pull-right-30[ ![](assets/images/val3.png) ] -- * `shiny::req()` checks input variable and silently stops execution --- name: download ## Download • Data * Add button and `downloadHandler()` function ``` shinyApp( ui=fluidPage( selectInput("data_input",label="Select data", choices=c("mtcars","faithful","iris")), textOutput("text_output"), downloadButton("button_download","Download") ), server=function(input, output) { getdata <- reactive({ get(input$data_input, 'package:datasets') }) output$text_output <- renderText(paste0("Selected dataset: ",input$data_input)) output$button_download <- downloadHandler( filename = function() { paste0(input$data_input,".csv") }, content = function(file) { write.csv(getdata(),file,row.names=FALSE,quote=F) }) }) ``` * Run in system browser if Rstudio browser doesn't work * See usage of download buttons --- name: download-plot ## Download • Plots ``` shinyApp( ui=fluidPage( selectInput("data_input",label="Select data", choices=c("mtcars","faithful","iris")), textOutput("text_output"), plotOutput("plot_output",width="400px"), downloadButton("button_download", "Download") ), server=function(input, output) { getdata <- reactive({ get(input$data_input, 'package:datasets') }) output$text_output <- renderText(paste0("Selected dataset: ",input$data_input)) output$plot_output <- renderPlot({hist(getdata()[, 1])}) output$button_download <- downloadHandler( filename = function() { paste0(input$data_input,".png") }, content = function(file) { png(file) hist(getdata()[, 1]) dev.off() }) }) ``` * Run in system browser if Rstudio browser doesn't work * See usage of download buttons --- name: module ## Modularizing Reactivity .size-95[ <img src="assets/images/shiny-mod.png" alt="drawing" width="800"/> ] --- name: end_slide class: end-slide, middle count: false # Thank you. Questions? Slide courtesy: Roy Francis (NBIS, RaukR2021) .end-text[ <p>R version 4.1.2 (2021-11-01)<br><p>Platform: x86_64-pc-linux-gnu (64-bit)</p><p>OS: Ubuntu 18.04.6 LTS</p><br> <hr> <span class="small">Built on : <i class='fa fa-calendar' aria-hidden='true'></i> 18-Jan-2022 at <i class='fa fa-clock-o' aria-hidden='true'></i> 09:51:25</span> <b>2022</b> • [SciLifeLab](https://www.scilifelab.se/) • [NBIS](https://nbis.se/) ]