用户选择主题 R shiny ggplot

Question

我希望用户能够为 ggplot 选择主题。我对非标准评估有点不稳定，但我猜这就是我所缺少的。任何建议表示赞赏。

library(shiny)
library(ggplot2)
themes <- ls("package:ggplot2", pattern = "^theme_")
themes <- themes[themes != "theme_get" &
  themes != "theme_set" &
  themes != "theme_replace" &
  themes != "theme_test" &
  themes != "theme_update"]
themes <- paste0(themes, "()")
# Define UI for application that draws a histogram
ui <- fluidPage(

  # Application title
  titlePanel("Old Faithful Geyser Data"),

  # Sidebar with a slider input for number of bins
  sidebarLayout(
    sidebarPanel(
      sliderInput("bins",
        "Choose bin width:",
        min = 5,
        max = 15,
        value = 10
      ),
      selectInput(
        "theme",
        "choose a theme",
        themes,
        selected = "theme_minimal()",
        multiple = FALSE
      )
    ),

    # Show a plot of the generated distribution
    mainPanel(
      plotOutput("distPlot")
    )
  )
)

# Define server logic required to draw a histogram
server <- function(input, output) {
  output$distPlot <- renderPlot({
    ggplot(faithful, aes(waiting)) +
      geom_histogram(binwidth = input$bins) +
      labs(title = input$theme) +
      input$theme
  })
}

# Run the application
shinyApp(ui = ui, server = server)
#> 
#> Listening on http://127.0.0.1:6760
#> Warning: Error in ggplot_add: Can't add `input$theme` to a ggplot object.

^{由 reprex package (v2.0.1)}

于 2022-05-05 创建

Answer 1

您可以使用 get() 从函数名称中获取函数：

server <- function(input, output) {
  output$distPlot <- renderPlot({
    ggplot(faithful, aes(waiting)) +
      geom_histogram(binwidth = input$bins) +
      labs(title = input$theme) +
      get(gsub("\(\)","",input$theme))()
  })

如果在主题列表中省略括号，则可以避免gsub

Answer 2

我认为这可以满足您的需求：

  output$distPlot <- renderPlot({
    ggplot(faithful, aes(waiting)) +
      geom_histogram(binwidth = input$bins) +
      labs(title = input$theme) +
      match.fun(stringr::str_sub(input$theme, 1, -3))()
  })

解释：

match.fun() 按名称查找函数。您需要从 input$theme 的值中删除 ()。因此调用 stringr::substr()。所以match.fun(stringr::str_sub(input$theme, 1, -3))给大家参考需要的主题功能。最后的()调用它。

用户选择主题 R shiny ggplot

user chooses theme R shiny ggplot

r

ggplot2

shiny