R降價和對象的閃亮交換

Question

我第一次創建R Markdown文檔，我想在一個文檔中呈現Markdown文本以及閃亮的組件，但我不知道如何交換對象減價和閃亮 - 任何幫助？

--- 
runtime: shiny 
output: html_document 
--- 
```{r echo=FALSE} 
subjects<-c(letters[1:20]) 
inputPanel(selectInput("subject_of_interest","",subjects)) 
selected_subject<-input$subject_of_interest # This is failing with error "Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)" 
``` 
The selected subject `r selected_subject` is..... 

我需要根據所選主題生成其他文本項目。有沒有辦法做到這一點？

Answer 1

以下將開始您以後的工作。

當你有一個selectInput你會想要一些東西是reactive即對用戶輸入作出反應。因此，您需要創建一個reactive function，它會將您之後的文字吐出。這將成爲你開始的基礎。

---

title: "Untitled" 
runtime: shiny 
output: html_document 
--- 

```{r, echo=FALSE} 
subjects <- c(letters[1:20]) 
inputPanel(
inputPanel(selectInput("subject","Select Subject",subjects,"a")) 
) 
subject <- reactive({ 
    paste0(
    "The selected subject ", 
    input$subject) 
}) 
output$text <- renderText({ 
      subject() 
    }) 
mainPanel(
     textOutput("text") 
    ) 
``` 

聯編輯

按照要求，道歉，如果你想在線：

--- 
title: "Untitled" 
runtime: shiny 
output: html_document 
--- 

```{r, echo=FALSE} 
subjects <- c(letters[1:20]) 
inputPanel(
inputPanel(selectInput("subject","Select Subject",subjects,"a")) 
) 
subject <- reactive({ 
    input$subject 
}) 
output$text <- renderText({ 
      subject() 
    }) 

``` 
the selected subject `r textOutput("text")`