如何在新引擎中包含地块 [英] How to include plots in a new engine

问题描述

我正在为knitr编写一个新引擎.该引擎可以根据输入生成作为ggplot对象(列表)或存储在文件(.png)中的图.我正在尝试将图像输出到knitr生成的html(pdf，md)文件中，但找不到方法.

I'm writing a new engine for knitr. This engine can, depending on the input, generate a plot as either a ggplot object (list) or stored in a file (.png). I'm trying to output the image to the html (pdf, md) file that is generated by knitr but cannot find how.

我尝试过:

• include_graphics()以及文件路径
• 在engine_output()函数中返回ggplot对象
• knit_print()有很多选择

• include_graphics() with the path of the file
• return the ggplot object in engine_output() function
• knit_print() with many options

什么都行不通！

这是引擎的代码.它是Ruby on GraalVM(Galaaz)的引擎.调用GalaazUtil.exec_ruby将在knitr的同一R进程上执行Ruby代码，并在out中返回执行的输出.

Here is the code of the engine. It's an engine for Ruby on GraalVM (Galaaz). Calling GalaazUtil.exec_ruby will execute the Ruby code on the same R process of knitr and return in out the output of the execution.

生成图时，没有输出... knitr 如何识别在R块中生成了图?

When a plot in generated, there is no output... how does knitr identify that a plot was generated in the R chunk?

现在假设我可以访问文件中生成的图像，那么如何在knitr html页面中显示该图像?

Now assuming that I have access to the generated image in a file, how to I make this show in my knitr html page?

eng_ruby = function(options) {
  block_code = paste(options$code, collapse = "\\n");
  code = paste0("GalaazUtil.exec_ruby(", 
                   shQuote(block_code), 
                  ")
                ");
  out = eval.polyglot("ruby", code);
  engine_output(options, block_code, out)
}

谢谢！

推荐答案

请参阅帮助页面?knitr::engine_output上的详细信息"部分.您可以使用knitr::include_graphics().这是一个玩具示例(包括R徽标):

Please see the "Details" section on the help page ?knitr::engine_output. You can use knitr::include_graphics(). Here is a toy example (include the R logo):

```{r}
knitr::knit_engines$set(Rlogo = function(options) {
  path = 'logo.jpg'
  file.copy(file.path(R.home('doc'), 'html', 'logo.jpg'), path)
  knitr::engine_output(options, out = list(knitr::include_graphics(path)))
})
```

```{Rlogo}
Whatever.
```

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