在knitr/rmarkdown中绘制为png [英] Plotly as png in knitr/rmarkdown

问题描述

以下 Rmarkdown 以 HTML 格式呈现 3D 图形，但不以 PDF 格式呈现.

The following Rmarkdown renders the plotly 3D graph in HTML, but not in PDF.

Testing plotly

```{r}
library(plotly)
p <- plot_ly(data=iris, x=~Sepal.Length, y=~Sepal.Width, z=~Petal.Length, 
             color=~Species, symbols=c(0,1), type="scatter3d", mode="markers")
p
```

图表的快照如下所示:

根据plotly 帮助页面:

如果您将 rmarkdown 与 HTML 输出一起使用，则在代码块中打印一个 plotly 对象将生成一个交互式 HTML 图形.当使用带有非 HTML 输出的 rmarkdown 时，打印一个 plotly 对象将导致图形的 png 屏幕截图.

If you are using rmarkdown with HTML output, printing a plotly object in a code chunk will result in an interactive HTML graph. When using rmarkdown with non-HTML output, printing a plotly object will result in a png screenshot of the graph.

有没有办法在 PDF 中渲染绘图?

Is there a way to render the plotly graph in a PDF?

注意: rmarkdown::render() 的错误是:

Error: Functions that produce HTML output found in document targeting latex output.
Please change the output type of this document to HTML. Alternatively, you can allow
HTML output in non-HTML formats by adding this option to the YAML front-matter of
your rmarkdown file:

  always_allow_html: yes

Note however that the HTML output will not be visible in non-HTML formats.

推荐答案

我创建了一个小变通方法，将绘图图像在本地保存为 png 文件并将其导入回 RMD 文件.您需要包 webshot，您可以通过以下方式加载:

I have created a little workaround, which saves the plotly images locally as png-file and imports it back to the RMD file. You need the package webshot, which you can load via:

install.packages("webshot")

另外，你需要通过安装phantomjs

Further more, you need to install phantomjs via

webshot::install_phantomjs()

然后(当 phantomjs 在你的 PATH 中时)，你可以创建你的 RMD 文件:

Then (when phantomjs is in your PATH), you can create your RMD file:

---
title: "Untitled"
output: pdf_document
---

```{r}
library(plotly)
p <- plot_ly(economics, x = ~date, y = ~unemploy / pop)

tmpFile <- tempfile(fileext = ".png")
export(p, file = tmpFile)
```
![Caption for the picture.](`r tmpFile`)

这对我有用..也许这对你来说也是一种解决方法！

This works for me .. perhaps it's a workaround for you, too!

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