Add n reactive radioButtons to shiny app depending on user input - r

Question

I am trying to create a shiny app in which the user can select variables from a data frame in order to subset the data. The output will (eventually) be a data table with the users subset. I need to create n number of input boxes depending on the number of variables the user selects for the subset. Ideally, the input boxes will be dynamic radio buttons (for subsetting factors). I have not yet gotten to printing the data frame, but I have been able to create multiple radio buttons. I have used to following code with the mtcars dataset to achieve this:
server.R
library(shiny)
shinyServer( function(input, output, session) {
output$variables <- renderUI({
numVar <- length(as.integer(input$in0))
lapply(1:numVar, function(i) {
list(radioButtons("dynamic", input$in0,
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()
))
The code creates n number of radio buttons; however, for some reason it defaults to printing two sets of buttons. Also, the name of each new set of buttons is always the name of the first variable selected. Moreover, selecting choice one in one set changes the choice of the other sets. I would like each radio button set to have a name corresponding to the variable in the data frame and I would like the choice of each button to be independent of the other selected buttons.

Answer 1

Your problem (see warnings) is that you always use same name for each radioButtons, while you should index them with i:
lapply(1:numVar, function(i) {
list(radioButtons(paste0("dynamic",input$in0[i]), input$in0[i],
choices = c("Choice one" = "one", "Choice two" = "two"), selected = "one"))
})
Or a bit more elegant:
lapply(input$in0, function(x) {
list(radioButtons(paste0("dynamic",x), x,
choices = c("Choice one" = "one",
"Choice two" = "two"), selected = "one"))
})