R + Shiny + conditionalPanel：在 UI 和服务器端组合条件

Question

我正在努力完成这项工作：当且仅当满足两个条件时，我想在闪亮的应用程序的侧边栏中显示一个按钮（称为“下载聚合数据”），即

(1) 我 select “显示额外按钮”下菜单中的“是”值

(2) select 编辑并显示在 table 中的数据至少有 20 行。

条件 (2) 是在“select 数据块”菜单中 selecting“large_chunk” 的结果，但我希望条件基于输出而不是在输入上。在我正在开发的实际应用程序中，我不会事先知道我将使用过滤器 select 多少数据行。

目前只实现了条件 (1)。

我在这里找到了一些关于 conditionalPanel 和服务器端条件的有用信息

Shiny - conditionalPanel - set condition as output from server

但我并没有走多远。感谢您的帮助！

library(shiny)
library(shinyWidgets)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(DT)
#> 
#> Attaching package: 'DT'
#> The following objects are masked from 'package:shiny':
#> 
#>     dataTableOutput, renderDataTable


df <- tibble(x=1:30, y=51:80, z=c(rep("small_chunk", 7), rep("large_chunk", 23)))


ui <- fluidPage(

  sidebarLayout(
         sidebarPanel(
            pickerInput("my_selection","Select data chunk",
                        choices=c("large_chunk", "small_chunk"),
                        selected="small_chunk",
                options = list(`actions-box` = TRUE,`selected-text-format` = "count > 3"),multiple = F),

            pickerInput("show","Show Extra Button",
                        choices=c("yes", "no"),
                        selected="yes",
                        options = list(`actions-box` = TRUE,`selected-text-format` = "count > 3"),multiple = F),

            
   conditionalPanel(
        condition = "input.show == 'yes' ",
            downloadButton("downloadData","Download aggregated data" ))
       
   ),

            
    

      mainPanel(

          DTOutput("table")
      )
 )            
     )


server <- function(input, output) {

    data_reactive <- reactive({

        df %>% filter(z %in% input$my_selection )
            

        
    })

    output$table <- renderDT({datatable(data_reactive())})

    
}





shinyApp(ui = ui, server = server)
#> PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.

静态 R Markdown 文档不支持闪亮的应用程序

^{由 reprex package (v2.0.1)}

于 2021-09-22 创建

Answer 1

你可以做到

output[["largeChunk"]] <- reactive({
  nrow(data_reactive()) >= 20
})
outputOptions(output, "largeChunk", suspendWhenHidden = FALSE)

并在 UI 中：

conditionalPanel(
  condition = "input.show == 'yes' && output.largeChunk",
  ......

R + Shiny + conditionalPanel：在 UI 和服务器端组合条件

R + Shiny + conditionalPanel: combining condition on UI and server side

r

shiny

server