从selecInput data.frame生成data.frame列表

Question

是否可以通过读取selectInput来为data.frame创建一个列表？

据我所知，一种方法是使用selectInput的选项在server.R中子集data.frame，而不是反过来。

我不能做一个预先制定的清单，因为我不知道有多少选择。所以我的应用程序应该：

selectInput Read data.frame，获取对竞选专栏的独特观察，并将其放入列表中，在中使用该列表

代码：

library(shiny)
library(tidyverse) 



shinyApp(

ui = fluidPage(
  selectInput("state", "Choose a state:",
              list(`East Coast` = c("NY", "NJ", "CT"),
                   `West Coast` = c("WA", "OR", "CA"),
                   `Midwest` = c("MN", "WI", "IA"))
  ),
  textOutput("result")
),
    server = function(input, output) {


      fb <- reactive({ 

        fb_data <- read_csv("https://www.dropbox.com/s/ry6gfksljbpg1d6/curacao-fb-julago.csv?dl=1", skip = 0)

      })


      lst_campaigns <- unique(fb()$campaign)  

      lst_campaigns
    }
  )

有关selectInput信息的链接：

https://shiny.rstudio.com/reference/shiny/latest/selectInput.html

Answer 1

是的，updateSelectInput做那个工作。

在下面的示例中，单击update按钮将调用读取dropbox文件并更新活动列表。请注意，我只传递了前十次战役的选择，因为第11项会导致错误(可能有一个不合法的字符，闪亮无法处理)。

library(shiny)
library(tidyverse) 

shinyApp(
  ui = fluidPage(
    selectInput("state", "Choose a state:",
                list(`East Coast` = c("NY", "NJ", "CT"),
                     `West Coast` = c("WA", "OR", "CA"),
                     `Midwest` = c("MN", "WI", "IA"))),
    actionButton("update", "Update"),
    textOutput("result")
  ),
  server = function(input, output, session) {


    fb <- reactive({ 
      fb_data <- read_csv("https://www.dropbox.com/s/ry6gfksljbpg1d6/curacao-fb-julago.csv?dl=1", skip = 0)
      fb_data
    })

    observeEvent(input$update, {
      dat = fb()
      lst_campaigns <- unique(dat$campaign) 
      updateSelectInput(session, "state",
                        choices=head(lst_campaigns, 10), 
                        selected=lst_campaigns[1])  
    })
  }
)

server用于自动启动。

server = function(input, output, session) {
    fb_data <- read_csv("https://www.dropbox.com/s/ry6gfksljbpg1d6/curacao-fb-julago.csv?dl=1", skip = 0)
    lst_campaigns <- unique(fb_data$campaign) 
    updateSelectInput(session, "state",
                      choices=head(lst_campaigns, 10), 
                      selected=lst_campaigns[1])  
}

Answer 2

您可以通过使用updateSelectInput和observe函数实现这一点，如下所示：

library(shiny)


ui <- fluidPage(
           selectInput("species", "Select a specie:", choices = NULL)
)

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

  data <- reactive({
    iris
  })

  observe({
    # Dont run unless a data have been imported 
    req(data())

    unique_obs <- levels(data()[, 'Species'])

    updateSelectInput(session = session, "species", choices = unique_obs)
  })
}

shinyApp(ui, server)