R闪亮：无法下载交互式报告

Question

我希望下载一个交互式 R 闪亮文档并将其保存到一个文件中以供其他用户（不拥有 R 或 Rstudio）查看和交互。 R 闪亮文档运行良好，但是当我尝试将下载的文件保存在某处时，下载按钮失败。这是我的代码；我使用了数据集“汽车”，因此可以重现错误：

闪亮的代码：

library(knitr)
library(shiny)
library(ggplot2)
library(readr)

x <- cars
x$dist_cut <- cut(x$dist, breaks = c(-1, 25, 50, 75, 100, 9999), 
                       labels = c("0-25", "26-50", "51-75", "76-100", ">100"))

t.cut <- table(x$dist_cut)

# Define UI for dataset viewer app ----
ui <- fluidPage(

  # App title ----
  titlePanel("Cars Data"),

  # Sidebar layout with a input and output definitions ----
  sidebarLayout( position = "right",

                 # Sidebar panel for inputs ----
                 sidebarPanel(

                   # Input: Selector for choosing dataset ----
                   selectInput(inputId = "dataset",
                               label = "Choose a range for dist:",
                               choices = c("show all", ">100", "76-100", "51-75", "26-50", "0-25")),
                   downloadButton('downloadReport')

                 ),

                 # Main panel for displaying outputs ----
                 mainPanel(

                   # Output: Barplot ----
                   plotOutput(outputId = "distPlot"),

                   # Output: HTML table with requested number of observations ----

                   DT::dataTableOutput("view")


                 )
  )
)

# Define server logic to summarize and view selected dataset ----
server <- function(input, output) {

  # Return the requested dataset ----
  datasetInput <- reactive({
    switch(input$dataset,
           "show all" = x,
           ">100" = x[x$dist_cut == ">100",],
           "76-100" = x[x$dist_cut == "76-100",],
           "51-75" = x[x$dist_cut == "51-75",],
           "26-50" = x[x$dist_cut == "26-50",],
           "0-25" = x[x$dist_cut == "0-25",])
  })

  # display the plot
  output$distPlot <- renderPlot({

    barplot(t.cut, beside = TRUE, col = c("green", "blue", "yellow", "orange", "red"), main = "Cars sorted by dist", ylim = c(0, 20), cex.main = 1.5, xlab = "dist", ylab = "Frequency")

  })

  # create the DT datatable
  output$view = DT::renderDataTable({
    DT::datatable(datasetInput(), filter = 'top', 
                  options = list(lengthMenu = c(5, 10, nrow(x)), pageLength = 5))

  })

  output$report <- downloadHandler(
    filename = function() paste0("report", ".html"),
    content = function(file) {
      tempReport <- file.path(tempdir(), "report.rmd")
      file.copy("report.rmd", tempReport, overwrite = TRUE)

      # Set up parameters to pass to Rmd document
      params <- list(data = x,
                     title = "Plot Title",
                     limits = c(-10,10))
      # Knit the document, passing in the `params` list, and eval it in a
      # child of the global environment (this isolates the code in the document
      # from the code in this app).
      rmarkdown::render(tempReport, output_file = file,
                        params = params,
                        envir = new.env(parent = globalenv())
      )
    }     
  )

}

# Create Shiny app ----
shinyApp(ui = ui, server = server)

降价代码：

---
output: html_document
params:
    data: NULL
    limits: NULL
    title: "Cars Data"
title: "`r params$title`"
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

```{r}
print(params$title)
barplot(table(params$x$dist_cut), beside = TRUE, col = c("green", "blue", "yellow", "orange", "red"), main = "Cars Split by dist", ylim = c(0, 20), cex.main = 1.5, xlab = "dist", ylab = "Frequency") 
library(DT) 
datatable(params$x, filter = 'top', options = list(lengthMenu = c(5, 10, nrow(x)), pageLength = 5))
```

使用此代码，我在单击下载按钮后收到以下警告和错误：

Warning: Error in : path for html_dependency not provided
  [No stack trace available]
Warning in min(w.l) : no non-missing arguments to min; returning Inf
Warning in max(w.r) : no non-missing arguments to max; returning -Inf
Warning in min(x) : no non-missing arguments to min; returning Inf
Warning in max(x) : no non-missing arguments to max; returning -Inf
Warning: Error in plot.window: need finite 'xlim' values

我还收到一个标题为“下载失败”的弹出窗口：

Error downloading {R shiny html link} - server replied: Internal Service Error

我花了大约一周的时间尝试调试它，但我还没有完全弄清楚我缺少什么。我是 R Shiny Web 应用程序的新手，我真的很想允许非 R 用户查看这些交互式报告以帮助他们完成工作。我希望这是足够的信息来帮助找到我的问题的解决方案。

谢谢！

更新：当我保存 HTML 文件并在 Internet Explorer 中打开它时，我只看到页面顶部的标题（汽车数据）和侧边栏面板（包含下拉框和下载按钮）。此外，我收到一条提示“Internet Explorer 限制此网页运行脚本或 ActiveX 控件”，当我按“允许阻止的内容”时没有任何反应。这和问题有关系吗？

对于最初没有发布可重现的示例，我深表歉意：这是我的第一篇 stackoverflow 帖子。

Answer 1

server replied: Internal Service Error 只是一个通用错误，这意味着您的.Rmd 无法正确呈现。您真正的问题可能出在您的.Rmd 上。

如果你查看堆栈跟踪错误，它会说：

Warning in min(w.l) : no non-missing arguments to min; returning Inf

当您单击下载按钮时，它会在您的 .Rmd 上运行 render 函数并尝试渲染它。从错误的外观来看，您正在尝试绘制某些东西，但是您的绘图函数试图用来制作绘图的部分或全部对象无法找到，因此它失败并出现错误。

由于您的绘图数据来自闪亮的应用程序，您必须将其传递到.Rmd。更好的方法是将.Rmd 需要的数据作为列表直接传递给rmarkdown::render 的params= 参数。

# NOTE: downloadHandler must be assigned to the ID of your downloadButton
output$downloadReport <- downloadHandler(
    filename = function() paste0("report", ".html"),
    content = function(file) {
        tempReport <- file.path(tempdir(), "report.rmd")
        file.copy("report.rmd", tempReport, overwrite = TRUE)

        # Set up parameters to pass to Rmd document
        #  these can be any time of R objects
        #  that you want your .Rmd to have access to
        params <- list(data = x,
                       title = "Plot Title",
                       limits = c(-10,10))
        # Knit the document, passing in the `params` list, and eval it in a
        #  child of the global environment (this isolates the code in the document
        #  from the code in this app).
        rmarkdown::render(tempReport, output_file = file,
                          params = params,
                          envir = new.env(parent = globalenv())
        )
    }     
)

现在在您的.Rmd 中，您可以在标题中定义这些参数：

---
output: html_document
params:
    data: NULL
    limits: NULL
    title: "Default title"
title: "`r params$title`"
---

然后通过访问params 对象来使用它。将对象作为param 传递到.Rmd 后，您可以使用您在参数列表中提供的名称在.Rmd 中访问它。因此，即使您的数据框在您的闪亮应用程序中被命名为x，由于您将它传递给参数data，您将使用params$data 在.Rmd 中访问它。

```{r}
print(params$title)
barplot(table(params$data$dist_cut), beside = TRUE,
        col = c("green", "blue", "yellow", "orange", "red"),
        main = "Cars Split by dist", ylim = c(0, 20),
        cex.main = 1.5, xlab = "dist", ylab = "Frequency")

library(DT)
DT::datatable(params$data, filter = 'top',
              options = list(lengthMenu = c(5, 10, nrow(params$data)),
                             pageLength = 5))
```

通过params 参数显式传递对象（并在新环境中呈现.rmd）确保您需要的数据对您的.rmd 可用，并且它具有正确 em> 数据（在 Shiny 中尤其重要，因为用户输入可能会导致对象的内容以意想不到的方式发生变化）并防止命名空间冲突（环境中存在具有相同名称的意外对象）