Shiny dynamic UI elements

app.R

library(shiny)

server <- function(input, output) {
  output$input_ui <- renderUI({
    num <- as.integer(input$num)
    
    lapply(1:num, function(i) {
      numericInput(paste0("n_input_", i), label = paste0("n_input", i), value = 0)
    })
  })
  
  output$table <- renderTable({
    num <- as.integer(input$num)
    
    data.frame(lapply(1:num, function(i) {
      input[[paste0("n_input_", i)]]
    }))
  })
  
}

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      selectInput("num", "select number of inputs", choices = seq(1,10,1))
    ),
    mainPanel(
      uiOutput("input_ui"),
      tableOutput("table")
    )
  )
)

shinyApp(ui = ui, server = server)