Question

I have been working on a side project that involves a simple shiny app that allows users to input the parameters of a dice roll for a board game then have the code preform 10,000 rolls with those parameters and present the average of the rolls. I have a basic code that successfully makes this happen but I am struggling how to make it into a shiny app to make accessible to others.

The issue I face is that in the server part of the shiny code I do not know how to store the intermediate results within a single reactive() function. Is there a local storage option that works with a repeating function?

The code I am using is:

# Define UI for application that draws a histogram
ui <- fluidPage(

   # Application title
   titlePanel("10,000 Roll Simulator"),

   # Sidebar with a slider input for number of bins 
   sidebarLayout(
      sidebarPanel(
         numericInput(inputId = "num_tac", label = "TAC", 
                      value =1 , min = 1, max = 20),
         numericInput(inputId = "num_def", label = "DEF", 
                      value =1 , min = 1, max = 10),
         numericInput(inputId = "num_arm", label = "ARM", 
                      value =0 , min = 0, max = 10)
      )
   )
)

server <- function(input, output){
 data()<- reactive({
   One_roll<- function(){dice <- sample(1:6, size = input$num_tac, replace = TRUE)
   return(sum((dice >= input$num_def)-input$num_arm))
   sims<-replicate(10000, One_roll()}
output$stats <- renderPrint({mean(data())})
}
# Run the application 
shinyApp(ui = ui, server = server)

Any help would be greatly appreciated, thank you!

Answer 1

您的代码存在一些问题：

data()<-是不允许的。请使用data<-，然后使用data()
在函数中使用input$绝对不是传递参数的正确方法

这是一个修改过的服务器函数，其中One_roll函数在被动内部定义，但在内部调用，输入作为参数传递：

server <- function(input, output){
  One_roll<- function(num_tac,num_def,num_arm){
    dice <- sample(1:6, size = num_tac, replace = TRUE)
    sum((dice >= num_def)-num_arm)
  }
  data<- reactive(replicate(10000, One_roll(input$num_tac,input$num_def, input$num_arm )))
  output$stats <- renderPrint(mean(data()))
}

您还需要textOutput函数中的ui来调用renderText，例如：

ui <- fluidPage(

  # Application title
  titlePanel("10,000 Roll Simulator"),

  # Sidebar with a slider input for number of bins 
  sidebarLayout(
    sidebarPanel(
      numericInput(inputId = "num_tac", label = "TAC", 
                   value =1 , min = 1, max = 20),
      numericInput(inputId = "num_def", label = "DEF", 
                   value =1 , min = 1, max = 10),
      numericInput(inputId = "num_arm", label = "ARM", 
                   value =0 , min = 0, max = 10)
    ), mainPanel = textOutput("stats")
  )
)

Answer 2

您还可以先将所有用户输入的数据保存到静态变量中，然后将它们用作普通变量。

server <- function(input, output) {

temp <- reactive({

  tac <- input$num_tac

  def <- input$num_def

  arm <- input$num_arm

  One_roll <- function(tac, def, arm) {

    dice <- sample(1:6, size = tac, replace = TRUE)

    sum((dice >= def) - arm)

  }

  data <- replicate(10000, One_roll(tac, def, arm))

  #remember to print the data again so the results will be saved to temp

  data

})

output$stats <- renderPrint({

  mean(temp())

})

}

How to Store Monte Carlo Simulation Outputs Within a reactive() Function In Shiny

2 个答案: