Question

我是Shiny的新手，我在SO上的类似问题的答案正在帮助我。

我想在下拉菜单中显示动态选项，具体取决于用户在单选按钮上选择的内容。但是下面的片段只能在用户选择时显示亚种的一种选择，首先是＃1动物类型，然后是＃2整体与亚种选择。

我有三个变量：＃1。动物类型（狮子与老虎）; ＃2。整体与亚种（radiobutton）; ＃3。亚种（如果用户在＃2中选择“整体”，那么亚种应该等于“不适用”）。

供参考：

老虎亚种= {孟加拉，西伯利亚}
狮子亚种= {巴巴里，西南非洲，德兰士瓦}

感谢任何帮助。感谢。

    library(shiny)
    if (interactive()) {

    ui <- fluidPage(
     selectizeInput("VarAnimal",
               label = "Animal",
               choices = c("Tiger", "Lion"),
               selected = "Tiger"),

     radioButtons("VarWholeOrSub", 
             "Whole or Sub",
              choices = c("Whole species", "Subspecies"),
              selected = "Whole species"), 

     selectizeInput("VarSubspecies",
               label = "Subspecies",
               choices = c("Not Applicable", "Bengal", "Siberian", "Barbary", "Southwest African", "Transvaal"),
               selected = "")
    )

    server <- function(input, output, session) {
    observe({
       x <- input$VarWholeOrSub

       if (input$VarWholeOrSub == "Whole species"){
         x <- c("Not Applicable")} else{
         x <- ifelse(input$VarAnimal == "Tiger", c("Bengal", "Siberian"), c("Barbary", "Southwest African", "Transvaal"))  
    }

      updateSelectizeInput(session,
                       "VarSubspecies",
                       choices = x)

    })
    }


    shinyApp(ui, server)
    }

Answer 1

问题来自使用ifelse(test, yes, no)当是或否有不同的测试时间时：

> ifelse("a"=="a", c("a","b"), c("b","a"))
[1] "a"
> ifelse(rep("a"=="a",2), c("a","b"), c("b","a"))
[1] "a" "b"

在您的情况下 - 有3种不同的长度 - 您应该使用if代替：

  if (input$VarWholeOrSub == "Whole species"){
    x <- c("Not Applicable")
    } else {
      if(input$VarAnimal == "Tiger")
        x <- c("Bengal", "Siberian")
      else
        x <- c("Barbary", "Southwest African", "Transvaal")
    }

Answer 2

ifelse的文档说明：

ifelse返回一个与test相同形状的值，该值填充了从yes或no中选择的元素，具体取决于test元素是TRUE还是FALSE。

library(shiny)
if (interactive()) {

  ui <- fluidPage(
    selectizeInput("VarAnimal",
                   label = "Animal",
                   choices = c("Tiger", "Lion"),
                   selected = "Tiger"),

    radioButtons("VarWholeOrSub", 
                 "Whole or Sub",
                 choices = c("Whole species", "Subspecies"),
                 selected = "Whole species"), 

    selectizeInput("VarSubspecies",
                   label = "Subspecies",
                   choices = c("Not Applicable", "Bengal", "Siberian", "Barbary", "Southwest African", "Transvaal"),
                   selected = "")
  )

  server <- function(input, output, session) {
    observe({

      if (input$VarWholeOrSub == "Whole species"){
        updateSelectizeInput(session, 'VarSubspecies', choices = c("Not Applicable"))
        } else{
          if(input$VarAnimal == "Tiger"){
            updateSelectizeInput(session, 'VarSubspecies', choices = c("Bengal", "Siberian"))
          } else if (input$VarAnimal == "Lion"){
            updateSelectizeInput(session, 'VarSubspecies', choices = c("Barbary", "Southwest African", "Transvaal"))
          }
        }
    })
  }


  shinyApp(ui, server)
}

Answer 3

几点：

（1）如前文所述，ifelse是罪魁祸首。 ?ifelse说

ifelse（测试，是，否）
ifelse返回一个相同形状的值作为test

在您的情况下，您应该按照建议使用if-else块。

（2）您可能希望在代码中使用较少的硬编码，通过分离数据（可能是全局的，以便以后您不需要更改R代码来更改数据）和获取摆脱一些冗余代码：

df <- data.frame(Animals = c("Tiger", "Lion"), 
                 WholeSpecies=rep("Not Applicable", 2),
                 SubSpecies=c("Bengal, Siberian", "Barbary, Southwest African, Transvaal"), 
                 stringsAsFactors = FALSE)
head(df)
#  Animals   WholeSpecies                            SubSpecies
#1   Tiger Not Applicable                      Bengal, Siberian
#2    Lion Not Applicable Barbary, Southwest African, Transvaal

library(shiny)
if (interactive()) {

  ui <- fluidPage(
    selectizeInput("VarAnimal",
                   label = "Animal",
                   choices = df$Animals,
                   selected = df$Animals[1]),

    radioButtons("VarWholeOrSub", 
                 "Whole or Sub",
                 choices = c("Whole species", "Subspecies"),
                 selected = "Whole species"), 

    selectizeInput("VarSubspecies",
                   label = "Subspecies",
                   choices = c(unique(df$WholeSpecies), unlist(strsplit(unique(df$SubSpecies), split=','))),
                   selected = "")
  )

  server <- function(input, output, session) {
    observe({

      x <- df[df$Animals==input$VarAnimal,]$WholeSpecies

      if (input$VarWholeOrSub == "Subspecies"){
        x <- unlist(strsplit(df[df$Animals==input$VarAnimal,]$SubSpecies, split=','))
      }

      updateSelectizeInput(session,
                           "VarSubspecies",
                           choices = x)

    })
  }

  shinyApp(ui, server)
}

在下拉菜单中，闪亮只显示一个选项（在几个中）

3 个答案: