r - Plotly as png in knitr/rmarkdown

Question

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
```

A snapshot of the graph appears as follows:

According to the plotly help page:

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.

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

Note: The error from rmarkdown::render() is:

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.

Answer 1

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")

Further more, you need to install phantomjs via

webshot::install_phantomjs()

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`)

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