如何将 "reactive" 数据作为参数传递给 R Markdown？

Question

我希望能够将反应式 data.table 传递到我的 Rmarkdown 文档，该文档将对 table 进行排序并打印顶部（例如 5）排序的条目。

我在 setorderv 将运行保存到 "Error : x must be a data.frame or data.table"。我怀疑反应性干扰了 is.data.table 检查。

我如何简单地将数据的副本传递给 Rmd 文档？并移除反应性包装器？

这是一个从反应性和 downloadHandler 库存示例中拼凑而成的简化示例。我查看了建议使用 observe 的 this on SO，但我不确定如何实现它。谢谢，我很感激这方面的帮助。

RMARKDOWN - SOtestreport.Rmd

---
title: "Top in Segment Report"
output: html_document
params:
  n: 5
  dt: NA
  top.field: NA
---


```{r setup, echo = FALSE}
library(data.table)
library(knitr) # for kable

```
Data report as at: `r format(Sys.time(), "%a %b %d %Y %X")`

```{r, echo = FALSE}
table.str <- paste0("Showing Top ", params$n ," tables for these fields: ", 
             params$top.field)

# is this the best way of having dynamic labels?
```
`r table.str`


```{r, echo = FALSE}
# tried this
# test.dt <- copy(dt)

# normally a function GenerateTopTable with limit sort field etc.
setorderv(dt, params$top.field, -1) # -1 is descending. THIS IS WHERE IT CRASHES
out <- dt[1:params$n,]

```


```{r toptable, echo = FALSE}

kable(out, digits = 3)

```

app.R

# SO test report
# mini example based on https://shiny.rstudio.com/gallery/reactivity.html

library(shiny)
library(datasets)

server <- function(input, output) {

  datasetInput <- reactive({
    switch(input$dataset,
           "rock" = rock,
           "pressure" = pressure,
           "cars" = cars)
  })

  output$caption <- renderText({
    input$caption
  })

  output$summary <- renderPrint({
    dataset <- datasetInput()
    summary(dataset)
  })

  output$view <- renderTable({
    head(datasetInput(), n = input$obs)
  })


  # PROBLEM BIT WHERE I AM ADDING ON GALLERY EXAMPLE
  # handler from 
  output$topreport <- downloadHandler(
    filename = "topreport.html",
    content = function(file) {
      # Copy the report file to a temporary directory before processing it, in
      # case we don't have write permissions to the current working dir (which
      # can happen when deployed).
      tempReport <- file.path(tempdir(), "SOtestreport.Rmd")
      file.copy("SOtestreport.Rmd", tempReport, overwrite = TRUE)

      # Set up parameters to pass to Rmd document
      #  TRIED THIS TOO
      #  my.dt <- as.data.table(datasetInput())
      my.dt <- datasetInput()
      my.params <- list(n = input$obs, 
                        dt = my.dt,
                        top.field = names(my.dt)[1])

      rmarkdown::render(tempReport, output_file = file,
                        params = my.params,
                        envir = new.env(parent = globalenv())
      )
    }
  )

Answer 1

我修复了这个例子 - Rmd 中的 dt 没有以 params$!

开头

setorderv(params$dt, params$top.field, -1) # -1 is descending
out <- params$dt[1:params$n,]

我仍在寻找上述方法是否正确的答案（将 Shiny 中的参数传递给 RMarkdown 应用程序）。

我还想向其他人指出这些答案也很有用：

@NicE 使用 ReactiveValues
What's the difference between Reactive Value and Reactive Expression?

我还利用复制数据集来打破反应性，即

my.dt <- copy(params$dt)
#do this before passing into render params list

RStudio 中的另一个提示是不要使用内部查看器窗格，而是在浏览器外部运行。这修复了临时文件的保存位置问题。您可以在下图中的运行应用程序下选择始终运行外部：

如何将 "reactive" 数据作为参数传递给 R Markdown？

How to pass "reactive" data into R Markdown as a parameter?

r

shiny

shiny-reactivity