Change output width of plotly chart size in R Markdown PDF output

Question

On a R markdown file, does someone know why out.width,out.height,figure.width and figure.height parameters doesn't change plotly charts size when producing a pdf file? ( I precise that such parameters works perfectly using plot function)

Please find below a reproductible example with a Rmarkdown file

On this example, I would like the plotly chart to occupy the entire sheet like the plot chart.

---
title: "Change chart size chart on pdf file using plotly"
output:
  pdf_document: default
---

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

```

## Parameters doesn't work with plotly  

```{r, out.width='100%',out.height='100%',fig.height=20, fig.width=15, fig.align="left"}
library(plotly)
plot_ly(x = cars[1:10,]$speed,y = cars[1:10,]$dist)
```

## Parameters works using plot function

```{r,out.width='130%',out.height='100%', fig.height=20, fig.width=15, fig.align="left"}
plot(cars[1:10,])
```

Answer 1

Plotly graphs are primarily designed for interactive outputs, and as such, can behave a bit strange when being exported to static images in PDF. This issue has had some similar posts in the past, and appears to come from how webshot creates the static image.

You can fix this by forcing the plotly graph dimensions when creating the graph. The plot_ly function has the arguments width and height which let you set the output dimensions of the resulting plot.

If you want to include HTML objects in PDF reports, you can use the webshot package which essentially takes a screenshot of the rendered plots and converts it into a static image for you to include in the report. This is explained well in the bookdown book. To install it, you will need to run:

install.packages('webshot')
webshot::install_phantomjs()

Once webshot is installed, it should work automatically:

---
title: "Change chart size chart on pdf file using plotly"
output:
  pdf_document: default
papersize: a4
---

```{r include=FALSE}
knitr::opts_chunk$set(echo = FALSE, warning = FALSE, message = FALSE)
library(plotly)
```

```{r, out.width="100%"}
plot_ly(x = cars[1:10,]$speed,y = cars[1:10,]$dist, width = 1000, height = 1200)
```

Will update this answer if I can work out exactly why it works, but hope that helps!