闪亮的应用程序中ggplots的动态数量

Question

I need your help, because I don't know how to solve my problem. I have my shiny app where I have data frame (imported from file) and checkboxgroupinput where I can mark which columns are for me interesting. After that in other tabpanel I would like to get two plot for each column (in one facet_wrap). All facet_wrap one under the other. The problem is that number of interesting columns is not constant. It is easy for my if I could hardcode number of rows with plots, but where it can change dynamically I have no idea how to program it, any tips from your side?

Answer 1

We can't solve your question without a reproducible example but you should be able to figure it out from this quick example of using uiOutput along with renderUI . This allows the use of dynamic values in UI elements.

Normally you would define your static input as checkboxGroupInput("columns", "Select the variables to plot", choices = vector_of_known_values) .

However as per your question, this doesn't work if the dataset is not known beforehand (eg: user file upload). In this case use uiOutput in the UI part: uiOutput("ui") , so that you delay evaluation to server side. In server side you can dynamically set the choices regardless of the data structure.

output$ui <- renderUI( {
  checkboxGroupInput("columns", "Select the variables to plot", choices = colnames(rv$data))
})

See full example:

library(shiny)
library(DT)
library(dplyr)

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      selectInput("datasets", "Select a dataset", choices = c("mtcars", "iris"), selected = "mtcars"),
      uiOutput("ui")
    ),
    mainPanel(
      DT::dataTableOutput("table")  
    )
  )
)

server <- function(input, output, session) {
  rv <- reactiveValues(data = NULL)

  observe( {
    rv$data <- eval(parse(text = input$datasets))
  })

  filtered <- reactive( {
    req(input$columns)
    if( all(!input$columns %in% colnames(rv$data))) {
      NULL
    } else {
      rv$data %>% select(input$columns) 
    }
  })

  output$ui <- renderUI( {
    checkboxGroupInput("columns", "Select the variables to plot", choices = colnames(rv$data))
  })

  output$table <- DT::renderDataTable( {
    req(filtered())
    DT::datatable(filtered())
  })
}

shinyApp(ui, server)