Shiny example app with dynamic number of plots

app.r

max_plots <- 5

ui <- fluidPage(

  headerPanel("Dynamic number of plots"),

  sidebarPanel(
    sliderInput("n", "Number of plots", value=1, min=1, max=5)
  ),

  mainPanel(
    # This is the dynamic UI for the plots
    uiOutput("plots")
  )
)

server <- function(input, output) {

  # Insert the right number of plot output objects into the web page
  output$plots <- renderUI({
    plot_output_list <- lapply(1:input$n, function(i) {
      plotname <- paste("plot", i, sep="")
      plotOutput(plotname, height = 280, width = 250)
    })

    # Convert the list to a tagList - this is necessary for the list of items
    # to display properly.
    do.call(tagList, plot_output_list)
  })

  # Call renderPlot for each one. Plots are only actually generated when they
  # are visible on the web page.
  for (i in 1:max_plots) {
    # Need local so that each item gets its own number. Without it, the value
    # of i in the renderPlot() will be the same across all instances, because
    # of when the expression is evaluated.
    local({
      my_i <- i
      plotname <- paste("plot", my_i, sep="")

      output[[plotname]] <- renderPlot({
        plot(1:my_i, 1:my_i,
             xlim = c(1, max_plots),
             ylim = c(1, max_plots),
             main = paste("1:", my_i, ".  n is ", input$n, sep = "")
        )
      })
    })
  }
}

shinyApp(ui, server)

Not sure, who is still looking for a solution, but here is a snippet that I use.

Refer full code snippet at -
https://gist.github.com/mayank7jan/0e89c1d6f48379881da607140f45b2ac

  
  observeEvent(rv$data_filtered, {
    
    uniPlot <- lapply(names(rv$data_filtered), function(col_i){
      ggplot(rv$data_filtered, aes_string(x=col_i)) + geom_bar(fill = "#8cd3ff") + theme_classic() + labs(title = col_i) + xlab(col_i) + ylab("Count")
    })
    
    output$univariate_plots <- renderUI({
      
      plot_output_list <- lapply(seq_along(1:length(uniPlot)),function(plot_i){
        column(width = 6,
               tags$div(style = "margin-top: 10px; margin-bottom: 10px;",
                        plotOutput(outputId = paste0("uni_", plot_i))
               ))
      })
      
      # Convert the list to a tagList - this is necessary for the list of items to display properly.
      do.call(tagList, plot_output_list)
      
      ## either works
      # plot_output_list
      
    })
    
    rv$uniPlot <- uniPlot
  })
  
  observeEvent(rv$uniPlot,{
    
    lapply(seq_along(1:length(rv$uniPlot)), function(plot_i) {
      output[[paste0("uni_", plot_i)]] <- renderPlot({
        rv$uniPlot[[plot_i]]
      })
    })
    
  }, ignoreInit = FALSE)
  

Output Preview :

Thanks for these great solutions. I have two questions please: How to ensure that the plots have the same legend to compare for example. The second thing is how to save all generated plots with one button click. Thanks

Hi @INTELLIGENTICA ,

1. The app then needs to then set to behave in a specific way only and lose some of its dynamicity. Or, Have tabs/select drop down for each of the columns in the uploaded data.frame to group/color by and thereby show the legend for.

2. To download all the generated plots with one click, there are multiple ways to do it -

1. Knit all plots in a report with either or all formats - HTML, pdf or excel
2. Have a download button for each plot
3. Save all the dynamically generated plots to local memory and then zip the whole directory for download.

Each of these is doable since the dynamic plots produced are available as individual list items in plot_output_list

I wanted to add another use case to this excellent gist. In my case I wanted to generate a dynamic number of graphs based on the factor levels of a column from a user input file. See also https://stackoverflow.com/questions/75250661/generate-dynamic-number-of-plots-based-on-factor-levels-of-user-input-file/75251212#75251212

library(shiny)
library(data.table)
library(ggplot2)
library(dplyr)

ui <- fluidPage(
  
  headerPanel("Dynamic number of plots"),
  
  sidebarPanel(
    fileInput("fileIn", 
              "Load input file",
              multiple = F)
  ),
  
  mainPanel(
    uiOutput("plot1")
  )
)

server <- function(input, output) {
  
  getData <- reactive({
    req(input$fileIn)
    dataIn <- as.data.frame(fread(input$fileIn$datapath))
    dataIn$plotGroup <- make.names(dataIn$plotGroup)
    return(dataIn)
  })
  
  output$plot1 <- renderUI({
    plotOutputList <- lapply(unique(getData()$plotGroup),
                             function(i){
                               plotname <- paste("plot", i, sep = "_")
                               plotOutput(plotname)
                             })
    do.call(tagList, plotOutputList)
  })
  
  observe({
  for(i in unique(getData()$plotGroup)){
    local({
      iCurrent <- i
      plotname <- paste("plot", iCurrent, sep = "_")
      
      output[[plotname]] <- renderPlot({
        getData() %>%
          filter(plotGroup == iCurrent) %>%
        ggplot(aes(x = xGroup, y = yVar)) +
          geom_point()
      })
    })
  }})
}

shinyApp(ui, server)