创建响应式 selectInput - 带有 Shiny 的 flexdashboard

Question

我正在尝试在 flexdashboard 文档中使用 Shiny 制作反应式 selectInput。

1. 我的第一个 selectInput 选择海洋公园的区域类型。

   selectInput("Zone", label = "Marine Park Zoning:",
             choices = c("All", levels(EoTR$MarineParkZone)), selected = "All")
   

2. 然后我使用此输入创建一个反应性数据框，其中仅包含在步骤 1 中选择的区域。

   zone.choices = reactive({
     if (input$Zone=="All"){
     select(EoTR, ReefName, MarineParkZone, MarineParkMgmtSection)
     }else{
     select(EoTR, ReefName, MarineParkZone, MarineParkMgmtSection)%>%
     filter(MarineParkZone==input$Zone)}
   })
   

3. 然后我尝试使用这个响应式数据框来定义我对下一个selectInput的选择

   reactive({
   selectInput("Reef", label = "Priority Reef:",
           choices = zone.choices()$ReefName, selected = "Arlington Reef (16-064)")
   })
   

当我运行文档时，我的第二个输入显示一堆代码而不是选择菜单，因此基于该选择器的所有进程都会失败。

下面是一些可以重现问题的代码

---
title: "Untitled"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
runtime: shiny 
---
```{r}
library(flexdashboard)
library(dplyr)

EoTR = data.frame(ReefName=c("Reef1", "Reef2", "Reef3", "Reef4"), 
              MarineParkZone=c("Fished", "Fished", "Un-Fished", "Un-Fished"))

selectInput("Zone", label = "Marine Park Zoning:",
          choices = c("All", levels(EoTR$MarineParkZone)), selected = "All")

zone.choices = reactive({
  if (input$Zone=="All"){
  select(EoTR, ReefName, MarineParkZone)
  }else{
  select(EoTR, ReefName, MarineParkZone)%>%
  filter(MarineParkZone==input$Zone)}
})

reactive({
selectInput("Reef", label = "Priority Reef:",
        choices = zone.choices()$ReefName, selected = "Reef1")
})
```

我知道我定义响应式输入的方式可能有些愚蠢，但我非常感谢任何帮助。

干杯，

山姆

Answer 1

以下是适合您的解决方案：

---
title: "Untitled"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
runtime: shiny 
---
```{r}
library(flexdashboard)
library(dplyr)

EoTR = data.frame(ReefName=c("Reef1", "Reef2", "Reef3", "Reef4"), 
              MarineParkZone=c("Fished", "Fished", "Un-Fished", "Un-Fished"))

selectInput("Zone", label = "Marine Park Zoning:",
          choices = c("All", levels(EoTR$MarineParkZone)), selected = "All")

zone.choices = reactive({
  if (input$Zone=="All"){
  EoTR
  }else{
  EoTR %>%
  filter(MarineParkZone==input$Zone)}
})


renderUI({selectInput("Reef", label = "Priority Reef:",
        choices = zone.choices()$ReefName, selected = "Reef1")})

```

问题在于您的selectInput("Reef"...)，您已将其设置为反应式（这是错误的）--> 您应该将其呈现为 UI 对象（renderUI）。