R 闪亮应用程序-多用途的反应式数据框&；延迟活动

我正在创建一个带有多个KPI值框的闪亮仪表板。我不会粘贴整个服务器/代码（>500行代码），但每个框都使用renderValueBox调用，我创建要使用的数据框“kpidat”（我对每个框都这样做），并使用if语句确定框的颜色和符号。请参见下面的示例代码：

output$incbox <- renderValueBox({

    area_prev<-as.character(input$dynamic2)
    prev_region<-input$select_B
    kpidat<-sept[sept$area==area_prev & sept$region==prev_region,]

    if(kpidat$`New TB incidents`[2]>kpidat$`New TB incidents`[1]){a<-"arrow-up";b<-"red"}
    if(kpidat$`New TB incidents`[2]<kpidat$`New TB incidents`[1]){a<-"arrow-down";b<-"green"}
    if(kpidat$`New TB incidents`[2]==kpidat$`New TB incidents`[1]){a<-"";b<-"yellow"}

    valueBox(
        paste0(kpidat$`New TB incidents`[2], "Incidents"), "Number of disease incidents.", 

        icon = icon(a),
        color = b
    )
})

---

output$incbox几个建议：


您可以将
kpidat
定义为一个反应对象，它将在
input$select\B
发生更改时更新。要在其他输出中使用它，请使用
kpidat（）
调用它。即使您在多个其他输出中使用它，
kpida中的表达式也非常好。谢谢你的帮助！我现在已经按照建议创建了一次被动函数来创建kpidat。我肯定也会研究trycatch，因为我以前从未听说过。非常感谢你的提示！
kpidat <- reactive({
  return(sept[sept$area==as.character(input$dynamic2) & sept$region==input$select_B,])
})

output$incbox <- renderValueBox({
  tryCatch({
    ## This will return if it can execute successfully
    local_kpidat <- kpidat()

    ## Only calculate these once
    foo <- local_kpidat$`New TB incidents`[2]
    bar <- local_kpidat$`New TB incidents`[1]

    if(foo >  bar){a<-"arrow-up";b<-"red"}
    if(foo <  bar){a<-"arrow-down";b<-"green"}
    if(foo == bar){a<-"";b<-"yellow"}

    valueBox(value = paste0(kpidat$`New TB incidents`[2], "Incidents"),
             subtitle = "Number of disease incidents.",
             icon = icon(a),
             color = b)

  }, error = function(e) {
    ## This, an empty value box, will be returned if any errors occur
    valueBox(value = "","")
  })
})

setDT(sept) ## conver sept to a data.table
setkey(sept,area,region,date) ## setkeys on sept to order it properly, I assume there is some kind of date value here?

## Calculate delta for all cases at once
sept[, Delta := `New TB incidents` - shift(`New TB incidents`, n = 1L, type = "lag")) , keyby = .(area,region)]

## Add a and be as columns for sept
sept[delta > 0,  `:=` (a = "arrow-up", b = "red"   )]
sept[delta < 0,  `:=` (a = "arrow-up", b = "green" )]
sept[delta == 0, `:=` (a = "",         b = "yellow")]

## setk key on area and region for faster subsets
setkey(sept,area,region)

## New version of reactive kpidat()

kpidat <- reactive({
  ## Return only the last (most recent) using data.table keys on area and region
  return( sept[.(as.character(input$dynamic2),input$select_B)][.N] )
})

output$incbox <- renderValueBox({
  tryCatch({
    ## This will return if it can execute successfully
    local_kpidat <- kpidat()

    valueBox(value = paste0(local_kpidat[,`New TB incidents`], "Incidents"),
             subtitle = "Number of disease incidents.",
             icon = local_kpidat[,a],
             color = local_kpidat[,b])

  }, error = function(e) {
    ## This, an empty value box, will be returned if any errors occur
    valueBox(value = "","")
  })
})