创建基于 R Shiny 中的输入更新的单选按钮

【问题标题】：Creating Radio Buttons that Update based on an Input in R Shiny创建基于 R Shiny 中的输入更新的单选按钮
【发布时间】：2017-06-17 01:17:46
【问题描述】：

我希望在闪亮的应用程序中创建一组单选按钮，这些单选按钮将根据用户输入进行更新。基本上，用户会选择一个问题，相应的答案选择将是单选按钮的更新选项。我无法让按钮更新。谁能指出我正确的方向？

非常抱歉，第一次使用这个网站。

到目前为止，我有：

questions <- read.csv("~/Answers.csv")
library(shiny)


ui <- fluidPage(

  selectInput("numberchoice",label = "Choose an image", choices = c(1:6), 
 selected = 1)
,
imageOutput("image")
,
radioButtons("answerchoice","",choiceNames = c("A","B","C","D","E"), 
choiceValues = questions[3,2:6])

)

server <- function(input,output,session) {
answers <- read.csv("~Answers.csv")
output$image <- renderImage(list(src=
paste("~",
input$numberchoice,".png", sep = "")
,contentType = "image/png", alt = "Face"),deleteFile = FALSE)
updateRadioButtons(session,"answerchoice",choices = 
questions[input$numberchoice,2:5]


}

shinyApp(ui = ui, server = server)`

【问题讨论】：

标签： r shiny

【解决方案1】：

您唯一需要做的就是对更改执行observe input$numberchoice 并在更改发生后更新radioButtons：

# observe input$numberchoice and update answer radioButtons accordingly
observeEvent(input$numberchoice, {
    updateRadioButtons(session,"answerchoice",choices = questions[input$numberchoice,2:5])
})

或者，如果你想避免observeEvent，你可以把整个答案输出放在服务器上，这样每次input$numberchoice改变时它都会更新：

用户界面：

uiOutput("answerchoice")

服务器：

output$answerchoice <- renderUI({
    radioButtons("answerchoice", "", choiceNames = c("A","B","C","D","E"), 
                 choiceValues = questions[input$numberchoice,2:5])
})

【讨论】：