r - 基于条件 react 逻辑 Shiny 的 flexdashboard

Question

我正在尝试根据某些输入连续进行一种渲染( renderPlot )或另一种渲染( renderText )。这是我尝试过的:

---
title: "Citation Extraction"
output: 
  flexdashboard::flex_dashboard:
    vertical_layout: scroll  
    orientation: rows
    social: menu
    source_code: embed
runtime: shiny
---

```{r setup, include=FALSE}
library(flexdashboard)
library(shiny)
```

Sidebar {.sidebar}
=====================================

```{r}
textInput("txt", "What's up?:")
```

Page 1
=====================================

### Chart A

```{r}
urtxt <- reactive({input$txt})

if (nchar(urtxt()) > 20){
    renderPlot({plot(1:10, 1:10)})
} else {
    renderPrint({
        urtxt()   
    })
}
```

但它指出:



所以我尝试在条件周围添加一个响应式(Reactive)，导致返回函数 reactive返回。

reactive({
    if (nchar(urtxt()) > 20){
    renderPlot({plot(1:10, 1:10)})
} else {
    renderPrint({
        urtxt()   
    })
}
})

我怎样才能有条件 react 逻辑？

Answer 1

要根据输入字符串的长度获得不同类型的输出，您可以执行以下操作:

1) 创建动态输出 uiOutput ,

2) 在 react 环境中 renderUI ，根据输入，选择输出的种类。

3) 渲染输出

---
title: "Citation Extraction"
output: 
flexdashboard::flex_dashboard:
vertical_layout: scroll  
orientation: rows
social: menu
source_code: embed
runtime: shiny
---

```{r setup, include=FALSE}
library(flexdashboard)
library(shiny)
```


Sidebar {.sidebar}
=====================================

```{r, echo = F}
textInput("txt", "What's up?:", value = "")
```

Page 1
=====================================

### Chart A

```{r, echo = F}
uiOutput("dynamic")

output$dynamic <- renderUI({ 
  if (nchar(input$txt) > 20) plotOutput("plot")
  else textOutput("text")
})

output$plot <- renderPlot({ plot(1:10, 1:10) })
output$text <- renderText({ input$txt })

```