前言
前面已经介绍了shinydashboard框架的标题栏和侧边栏的输入项部分，这节介绍一下侧边栏的菜单项（menu items），侧边栏的菜单项主要用于切换不同的主体界面，点击不同的菜单项，主体呈现出不同的界面内容。
【R语言】shinydashboard系列一：标题栏
【R语言】shinydashboard系列二：侧边栏--输入项
菜单项menu items
菜单项分类
侧边栏的菜单项可以分为静态菜单项和动态菜单项，注意这里说的静态和动态说的是书写代码的时候，而不是对于呈现的结果。静态菜单项用到两个函数：sidebarMenu()和tabItems()，动态菜单项用到上一节讲到的一对输出函数：sidebarMenuOutput()和renderMenu()。
注意
静态菜单项：sidebarMenu()函数写在ui脚本dashboardSidebar()中，tabItems()函数写在dashboardBody()中；动态菜单项：输出项sidebarMenuOutput()函数写在ui脚本dashboardSidebar()中，renderMenu()函数写在server脚本中与之对应。
静态菜单项
静态菜单项主要用到两个函数：sidebarMenu()和tabItems()，sidebarMenu()函数写在dashboardSidebar()函数中，tabItems()函数写在dashboardBody()中，两种通过tabName相互对应。例如：
library(shiny)library(shinydashboard)library(ggplot2)library(DT)ui <- dashboardPage( dashboardHeader(title = "Flash WorkingNotes"), dashboardSidebar( sidebarMenu( menuItem("Data", tabName = "Data", icon = icon("dashboard")), menuItem("Summary", tabName = "Summary",icon = icon("th"), badgeColor = "green"), menuItem("Plot", tabName = "Plot", icon = icon("bar-chart-o")), menuItem("Plot1", tabName = "Plot1", icon = icon("bar-chart-o")) )), dashboardBody( tabItems( tabItem(tabName = "Data", box(dataTableOutput("Data"), width = 100)), tabItem(tabName = "Summary",verbatimTextOutput("Summary")), tabItem(tabName = "Plot", plotOutput("Plot")), tabItem(tabName = "Plot1",plotOutput("Plot1"))) ))server <- function(input, output) { set.seed(123) data = diamonds[sample(1:nrow(diamonds), 10000, replace = F), ] output$Data <- renderDataTable({datatable(data)}) output$Summary <- renderPrint({str(data)}) output$Plot <- renderPlot({ ggplot(data, aes(x = price, fill = cut)) geom_histogram(position = "fill", bins = 30) ggtitle("histogram plot") theme(plot.title = element_text(hjust = 0.5)) xlab("") }) output$Plot1 <- renderPlot({ ggplot(data = data, aes(x = carat, y = price, colour = color)) geom_point() ggtitle("scatter diagram") theme(plot.title = element_text(hjust = 0.5)) })}shinyApp(ui, server)注意上面sidebarMenu()和tabItems()书写位置，sidebarMenu()中的menuItem与tabItems()中的tabItem成对出现，通过tabname一一对应。
上面4个菜单项：Data菜单项呈现原数据，Summary菜单项查看数据字段类型，Plot菜单项绘制直方图，Plot1菜单项绘制散点图。上述代码运行结果：
动态菜单项
动态菜单项通过sidebarMenuOutput()和renderMenu()实现。sidebarMenuOutput()写在ui中的dashboardSidebar()中，renderMenu()写在server中与之对应，两者通过变量名匹配。
library(shiny)library(shinydashboard)library(ggplot2)library(DT)
ui <- dashboardPage( dashboardHeader(title = "Flash WorkingNotes"), dashboardSidebar(sidebarMenuOutput("menu")), dashboardBody( tabItems( tabItem(tabName = "Data", box(dataTableOutput("Data"), width = 100)), tabItem(tabName = "Summary",verbatimTextOutput("Summary")), tabItem(tabName = "Plot", plotOutput("Plot")), tabItem(tabName = "Plot1",plotOutput("Plot1")))))
server <- function(input, output) { set.seed(123) data = diamonds[sample(1:nrow(diamonds), 10000, replace = F), ] output$menu <- renderMenu({ sidebarMenu( menuItem("Data", tabName = "Data", icon = icon("dashboard")), menuItem("Summary", icon = icon("th"), tabName = "Summary",badgeColor = "green"), menuItem("Plot", tabName = "Plot", icon = icon("bar-chart-o")), menuItem("Plot1", tabName = "Plot1", icon = icon("bar-chart-o")) ) }) output$Author <- renderText({paste("The Author:", input$text)}) output$Data <- renderDataTable({datatable(data)}) output$Summary <- renderPrint({str(data)}) output$Plot <- renderPlot({ ggplot(data, aes(x = price, fill = cut)) geom_histogram(position = "fill", bins = 30) ggtitle("histogram plot") theme(plot.title = element_text(hjust = 0.5)) xlab("") }) output$Plot1 <- renderPlot({ ggplot(data = data, aes(x = carat, y = price, colour = color)) geom_point() ggtitle("scatter diagram") theme(plot.title = element_text(hjust = 0.5)) })}shinyApp(ui, server)注意上面sidebarMenuOutput()和renderMenu()的书写位置，两者通过menu变量名匹配。
总结
恭喜勇士，进入西决！！！将侧边栏的输入项和菜单项介绍完整。菜单项用于切换主体呈现的界面，输入项用于改变主体呈现的内容，书写代码的时候菜单项有静态菜单项和动态菜单项。重点注意菜单项和输入项以及对应的输出项函数的书写位置，即可灵活使用。最后上传一下文章开头动态图的代码。
library(shiny)library(shinydashboard)library(ggplot2)library(DT)ui <- dashboardPage( dashboardHeader(title = "Flash WorkingNotes"), dashboardSidebar( sidebarMenu( menuItem("Data", tabName = "Data", icon = icon("dashboard")), menuItem("Summary", icon = icon("th"), tabName = "Summary",badgeColor = "green"), menuItem("Plot", tabName = "Plot", icon = icon("bar-chart-o")), menuItem("Plot1", tabName = "Plot1", icon = icon("bar-chart-o")) )), dashboardBody( tabItems( tabItem(tabName = "Data", box(dataTableOutput("Data"), width = 100)), tabItem(tabName = "Summary",verbatimTextOutput("Summary")), tabItem(tabName = "Plot", plotOutput("Plot")), tabItem(tabName = "Plot1",plotOutput("Plot1"))) ))
server <- function(input, output) { set.seed(123) data = diamonds[sample(1:nrow(diamonds), 10000, replace = F), ] output$Author <- renderText({paste("The Author:", input$text)}) output$Data <- renderDataTable({datatable(data)}) output$Summary <- renderPrint({str(data)}) output$Plot <- renderPlot({ ggplot(data, aes(x = price, fill = cut)) geom_histogram(position = "fill", bins = 30) ggtitle("histogram plot") theme(plot.title = element_text(hjust = 0.5)) xlab("") }) output$Plot1 <- renderPlot({ ggplot(data = data, aes(x = carat, y = price, colour = color)) geom_point() ggtitle("scatter diagram") theme(plot.title = element_text(hjust = 0.5)) })}shinyApp(ui, server)
