R 在shiny 的图中添加动态数量的轨迹

如上所述，这是我之前答案here的副本.

然而，@YBS的方法过于复杂，我想提供直接比较的可能性.对于ggplot或plotly，最好使用长格式的data.frame(例如，使用data.table::melt从宽转换为长).这样，我们可以使用plot_ly的split、name或color参数基于数据创建多条记录道:

library(shiny)
library(shinydashboard)
library(plotly)
library(gapminder)

DF <- gapminder[, c(1, 3, 4)]

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(
    selectizeInput(
      "col",
      "Pick a column for y-axis to plot, if ticked in checkbox below",
      choices = NULL,
      selected = NULL,
      multiple = TRUE
    ),
    checkboxGroupInput("chk", "Display Plot", choices = DF$country[1])
  ),
  dashboardBody(tabsetPanel(id = "tabs",
                            tabPanel(
                              "Plot data" , plotlyOutput("tseries")
                            )))
)

server <- function(input, output, session) {
  freezeReactiveValue(input, "col")
  
  # server-side selectize for improved performance
  updateSelectizeInput(
    session,
    "col",
    choices = DF$country,
    selected = DF$country[1],
    server = TRUE
  )
  
  observeEvent(input$col, {
    updateCheckboxGroupInput(
      session,
      "chk",
      "Select item to plot",
      choices = input$col,
      selected = input$col
    )
  })
  
  output$tseries <- renderPlotly({
    if (is.null(input$chk)) {
      plotly_empty(type = 'scatter', mode = 'lines')
    } else {
      plot_ly(
        DF[DF$country %in% input$chk, ],
        type = 'scatter',
        mode = 'lines',
        x = ~ year,
        y = ~ lifeExp,
        split = ~ country
      )
    }
  })
}

shinyApp(ui, server)