尝试使用R中的闪亮应用程序创建一个未来值计算器并得到错误：“ cat”无法处理参数1（类型“ closure”）

Question

This is the code I have on my server file:

shinyServer(function(input, output) {
  output$P = renderText(input$Slider1)
  output$n = renderText(input$numeric1)
  output$r = renderText(input$numeric2/100)

futureValue <- reactive({
   principal <- output$P
   numberOfPeriods <- output$n
   rate <- output$r
   fvalue <- principal*(((1+rate)^numberOfPeriods-1)/rate)
   return(fvalue)
   })

output$fv <- renderText(futureValue)

})

Code for main panel on UI File:

sidebarPanel(
h4("Select Monthly Investment Amount:"),
sliderInput("Slider1","Select Monthly Investment Amount:", 100, 1000, 
100),    
numericInput("numeric1", "Select Number of Payments:", value = 12, min 
= 6, max = 60, step = 1),
numericInput("numeric2", "Select Interest Rate Percentage:", value = 
3.0, min = 0.1, max = 5.0, step = 0.1)  

mainPanel
(
    h4("Monthly Investment Amount:"),
    textOutput("P"),

    h4("Number of Periods:"),
    textOutput("n"),

    h4("Interest Rate:"),
    textOutput("r"), 

    h4("Under the given circumstances, the future value of your 
    investment is:"),

    textOutput("fv")
)

Everything works except for the last part where I'm performing the calculations for future value. Would anyone be able to tell me what I'm doing wrong?

Answer 1

Hi reactivs are functions not variables

output$fv <- renderText(futureValue() ) 

and change the reactive function like this

futureValue <- reactive({ 
  principal <- input$Slider1     
  numberOfPeriods <- input$numeric1 
 rate <- input$numric2 
 fvalue <-principal*(((1+rate)^numberOfPeriods-1)/rate) 
 return(fvalue) })

should solve it.

Hope this helps!