SelectInput Value update based on previous SelectInput in R shiny

Question

下面的 R shiny 脚本创建了三个 select 输入，每个 select 输入的值都取决于前一个 select 输入的输入值。例如。在脚本中的数据中，"value" 列值取决于 "Candy" 列，而 "Candy" 列值取决于 "Brand"。问题是，无论我 select "Mars" 还是 "Netle" 值在 "Brand" 列中，相应的 "Candy" 值“100Grand”对于两者都是相同的，因此由于 select 输入正在读取相同的值，因此我没有看到值列中的变化。请帮我解决这个问题，也请确保脚本不会变慢。谢谢

candyData <- read.table(
text = "
Brand       Candy           value
Mars        100Grand        Choc1
Netle       100Grand        Choc2
Nestle      Crunch          Choc3",
header = TRUE,
stringsAsFactors = FALSE)
library(shiny)
library(shinydashboard)
submenuUI <- function(id) {
ns <- NS(id)
tagList(
box(title = "Data", status = "primary", solidHeader = T, width = 12,
    fluidPage(
      fluidRow(

        column(2,offset = 0, style='padding:1px;',

selectInput(ns("Select1"),"select1",unique(candyData$Brand))),
        column(2,offset = 0,

style='padding:1px;',selectInput(ns("Select2"),"select2",choices = NULL)),
        column(2, offset = 0,

style='padding:1px;',selectInput(ns("Select3"),"select3",choices=NULL ))
      )))
)
}
submenuServ <- function(input, output, session){
observeEvent(input$Select1,{
updateSelectInput(session,'Select2',
choices=unique(candyData$Candy[candyData$Brand==input$Select1]))
})
observeEvent(input$Select2,{
updateSelectInput(session,'Select3',
choices=unique(candyData$value[candyData$Brand==input$Select1 &
candyData$Candy==input$Select2]))
})
}
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(
  shinyjs::useShinyjs(),
  id = "tabs",
  menuItem("Charts", icon = icon("bar-chart-o"),
           shinyjs::hidden(menuSubItem("dummy", tabName = "dummy")),
           menuSubItem("Sub-item 1", tabName = "subitem1")
  ))),
dashboardBody(
tabItems(tabItem("dummy"),
         tabItem("subitem1", submenuUI('submenu1'))
)
))
server <- function(input, output,session) {
callModule(submenuServ,"submenu1")
}
shinyApp(ui = ui, server = server)

Answer 1

您只需在 observeEvent 中添加 input$Select1 即可更新 select3

submenuServ <- function(input, output, session){
    observeEvent(input$Select1,{
        updateSelectInput(session,'Select2',
                          choices=unique(candyData$Candy[candyData$Brand==input$Select1]))
    })
    observeEvent(c(input$Select1, input$Select2),{
        updateSelectInput(session,'Select3',
                          choices=unique(candyData$value[candyData$Brand==input$Select1 &
                                                             candyData$Candy==input$Select2]))
    })
}

如果需要，可以将 observeEvent 转换为 observe :

observe({
    updateSelectInput(
        session, 'Select3',
        choices= unique(candyData$value[candyData$Brand==input$Select1 & candyData$Candy==input$Select2])
    )
})

SelectInput Value update based on previous SelectInput in R shiny

SelectInput Value update based on previous SelectInput in R shiny

r

shiny

shinydashboard

shinyapps