R 更新应用程序时保持绘图图例切换

我有一个闪亮的应用程序，它使用plotly。我希望应用程序在通过选择新输入更新绘图时保持当前图例切换

要了解我所追求的行为，这里有一个应用程序：

library(shiny)
library(plotly)

data(diamonds, package = "ggplot2")
nms <- names(diamonds)

ui <- fluidPage(

    headerPanel("Diamonds Explorer"),
    sidebarPanel(
        sliderInput('sampleSize', 'Sample Size', min = 1, max = nrow(diamonds),
                                value = 1000, step = 500, round = 0),
        selectInput('x', 'X', choices = nms, selected = "carat"),
        selectInput('y', 'Y', choices = nms, selected = "price"),
        selectInput('color', 'Color', choices = nms, selected = "clarity"),

        selectInput('facet_row', 'Facet Row', c(None = '.', nms), selected = "clarity"),
        selectInput('facet_col', 'Facet Column', c(None = '.', nms)),
        sliderInput('plotHeight', 'Height of plot (in pixels)', 
                    min = 100, max = 2000, value = 1000)
    ),
    mainPanel(
      plotlyOutput('trendPlot', height = "900px")
    )
)

server <- function(input, output) {

  #add reactive data information. Dataset = built in diamonds data
  dataset <- reactive({
    diamonds[sample(nrow(diamonds), input$sampleSize),]
  })

  output$trendPlot <- renderPlotly({

    # build graph with ggplot syntax
    p <- ggplot(dataset(), aes_string(x = input$x, y = input$y, color = input$color)) + 
      geom_point()

    # if at least one facet column/row is specified, add it
    facets <- paste(input$facet_row, '~', input$facet_col)
    if (facets != '. ~ .') p <- p + facet_grid(facets)

    ggplotly(p) %>% 
      layout(height = input$plotHeight, autosize=TRUE)

  })

}

shinyApp(ui, server)

库（闪亮）
图书馆（绘本）
数据（菱形，package=“ggplot2”）
网络管理系统