状态与完善 UI

良好 UI 的一个原则是直观地使用颜色。幸运的是，shinydashboard 允许在部分 shinydashboard 元素中设置状态。这可以通过为适当的元素（如 box()、notificationItem()、dropdownMenu()）添加 status 参数来完成，不过后两者不会在本课程中讲解。

设置 status = "success" 会呈现绿色，status = "danger" 会呈现红色，status = "warning" 为橙色，等等。

本练习是课程的一部分

使用 shinydashboard 构建仪表板

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练习说明

将第三行第一个 box 的状态改为 "success"。
参考第 28 到 33 行（第二行 ValueBox() 的取值），对第三行的对应部分做相同处理。
定义上一步中命名为 "line" 的 plotly 对象的输出。
使用刚定义的 ui 和 server 渲染 shinydashboard。

交互式实操练习

通过完成这段示例代码来试试这个练习。

header <- dashboardHeader(title = "Portfolio information")
sidebar <- dashboardSidebar(disable = TRUE)

body <- dashboardBody(
          fluidRow(box(selectInput("stock", "Stock name", choices = c("AAPL", "DIS")))),
          fluidRow(valueBoxOutput("name", width = 2), 
                   valueBoxOutput("open", width = 2), 
                   valueBoxOutput("close", width = 2), 
                   valueBoxOutput("high", width = 2), 
                   valueBoxOutput("low", width = 2), 
                   valueBoxOutput("vol", width = 2)),
          # Change status to "success"
          fluidRow(box("This stock is in your portfolio", width = 2, status = "danger"), 
                   valueBoxOutput("open_pct", width = 2), 
                   valueBoxOutput("close_pct", width = 2), 
                   valueBoxOutput("high_pct", width = 2), 
                   valueBoxOutput("low_pct", width = 2), 
                   valueBoxOutput("vol_pct", width = 2)),
          fluidRow(box(plotlyOutput("line")), 
                   box(radioButtons("feature", "Features", 
                       choiceNames = c("Open", "Close", "High", "Low", "Volume"),
                       choiceValues = c("open", "close", "high", "low", "volume")) ) )
          )

ui <- dashboardPage(header, sidebar, body)

server <- function(input, output) {
  output$name <- renderValueBox(valueBox("Stock name", get_name(input$stock), color = "black"))
  output$open <- renderValueBox(valueBox("Open price", most_recent(input$stock, "open"), color = "black"))
  output$close <- renderValueBox(valueBox("Close price", most_recent(input$stock, "close"), color = "black"))
  output$high <- renderValueBox(valueBox("High", most_recent(input$stock, "high"), color = "black"))
  output$low <- renderValueBox(valueBox("Low", most_recent(input$stock, "low"), color = "black"))
  output$vol <- renderValueBox(valueBox("Volume", most_recent(input$stock, "volume"), color = "black"))
  # Specify the values for ValueBoxes in the third row
  output$open_pct <- ___(valueBox("Change", paste0(most_recent_pct(input$stock, "open"),"%"), color = box_color(most_recent_pct(input$stock, "open"))))
  ___ <- ___(___("Change", paste0(most_recent_pct(input$stock, "close"),"%"), color = box_color(most_recent_pct(input$stock, "close"))))
  ___ <- ___(___("Change", paste0(most_recent_pct(input$stock, "high"),"%"), color = box_color(most_recent_pct(input$stock, "high"))))
  ___ <- ___(___("Change", paste0(most_recent_pct(input$stock, ___),"%"), color = box_color(most_recent_pct(input$stock, ___))))
  ___ <- ___(___("Change", paste0(most_recent_pct(___, ___),"%"), color = box_color(most_recent_pct(___, ___))))
  # Plotly object in the fourth row
  ___ <- ___(plot_line(input$stock, input$feature))
}

# Render the dashboard using shinyApp()
___

编辑并运行代码