I am rendering numericInput widgets in a Shiny app using the lapply function in a renderUI environment. The amount of numericInput widgets depends on the amount of elements in a sublist. Said list contains the parametres of a distribution, i.e.:

normal -> mean, sd

betagen -> shape1, shape2, min, max.

So, for the 'normal' element I would need two widgets rendered and for 'betagen' four.

The problem however is that the corresponding labels don't show up for each widget. Furthermore, if I try and assign a unique inputId to each numericInput I get an error.

Here is a MWE of the code I'm using. I have tried using names() to get the list element names as the label but nothing shows up. Any help would be appreciated.

MWE

library(shiny)

# Lists containing the distribution parametres
lNormal <-list(mean=10, sd=20)# Easily identifiable values for debugging
lBetagen <-list(shape1=10 , shape2=20, min=30, max=40)# Easily identifiable values for debugging

# List of lists
lDists <- list(normal=lNormal, betagen=lBetagen)



# UI
ui <- fluidPage(

    sidebarLayout(
        sidebarPanel(
            uiOutput("ui1")
        ),

        mainPanel()
    )
)

# Server
server <- function(input, output) {

        output$ui1 <- renderUI({
            
            # index pointing to a distribution in lDists
            i <- 2
            
            # Render numeric inputs for each element of IDs
            lapply(lDists[[i]], function(x){numericInput(inputId = "id",# names(x) -> results in an error
                                                 label = names(x),# the names don't show up as labels
                                                 value = x,
                                                 step = 0.1
                                                 )}
            )
        })
    
}

# Run the application 
shinyApp(ui = ui, server = server)

CodePudding user response：

You should use mapply instead of lapply:

mapply(
  function(x, y){
    numericInput(
      inputId = y,
      label = y,
      value = x,
      step = 0.1
    )
  },
  x = lDists[[i]], 
  y = names(lDists[[i]]),
  SIMPLIFY = FALSE
)

or you could use purrr::imap:

purrr::imap(lDists[[i]], ~numericInput(inputId = .y, label = .y, value = .x, step = 0.1))