Access input ID of reactive radioButtons in shiny app - r

Question

I am trying to create a shiny app which includes radioButtons which are reactive to some user input.
I was successful to implement the code from this related question:
Add n reactive radioButtons to shiny app depending on user input
However, in this question it is not described how to access this values.
Here is the example:
server.R
library(shiny)
shinyServer( function(input, output, session) {
output$variables <- renderUI({
numVar <- length(as.integer(input$in0))
lapply(input$in0, function(x) {
list(radioButtons(paste0("dynamic",x), x,
choices = c("Choice one" = "one",
"Choice two" = "two"), selected = "one"))
})
})
})
ui.R
library(shiny)
shinyUI(pageWithSidebar (
headerPanel("mtcars subset"),
sidebarPanel(
selectInput(inputId = 'in0', label = 'Choose variables',
choices = colnames(mtcars),
multiple = TRUE, selectize = TRUE),
uiOutput("variables")
),
mainPanel()
))
What I have tried so far:
numVar <- length(as.integer(input$in0))
for(i in 1:numVar){
in <- noquote(paste0("dynamic",input$in0[i]))
input$in
}
However, this does not work. Any suggestions?

Answer 1

I'm not sure exactly of your use case but to access the values you could edit your code as below:
numVar <- length(as.integer(input$in0))
for(i in 1:numVar){
value <- paste0("dynamic",input$in0[i])
input[[value]]
}
Basically you need to use input[[value]] as opposed to input$value in this case. It doesn't seem that R allows you to use in as a variable (probably because it's already used in other contexts). You don't need noquote() anymore.

Answer 2

Welcome to stackoverflow!
You were almost there. However, you'll have to make sure, that you are accessing the inputs in a reactive context.
Here is a working example:
library(shiny)
ui <- fluidPage(
pageWithSidebar (
headerPanel("mtcars subset"),
sidebarPanel(
selectInput(inputId = 'in0', label = 'Choose variables',
choices = colnames(mtcars),
multiple = TRUE, selectize = TRUE),
uiOutput("variables")
),
mainPanel(
textOutput("myChoicesDisplay")
)
)
)
server <- function(input, output, session) {
output$variables <- renderUI({
lapply(input$in0, function(x) {
list(radioButtons(paste0("dynamic", x), x,
choices = c("Choice one" = "one",
"Choice two" = "two"), selected = "one"))
})
})
myChoices <- reactive({
dynInputList <- list()
for(dynInputs in paste0("dynamic", input$in0)){
dynInputList[[dynInputs]] <- input[[dynInputs]]
}
return(dynInputList)
})
output$myChoicesDisplay <- renderText({
paste(input$in0, myChoices(), sep = ": ", collapse = ", ")
})
}
shinyApp(ui, server)