R markdown df_print options
<p>I have a R markdown document in RStudio, where a data.table is printed.  I want to set the data frame print options to control printed number of rows and columns, as described <a href="http://rmarkdown.rstudio.com/html_document_format.html#data_frame_printing" rel="noreferrer">here</a>.</p>

<p>Here is a minimal example .Rmd file:</p>

<pre><code>---
output: 
  html_document: 
    fig_height: 8
    fig_width: 10
    df_print: paged
---

```{r}
knitr::opts_chunk$set(echo = FALSE)
cars
```
</code></pre>

<p><strong>Where/how do I set the <code>rows.print</code> option?</strong></p>

<p>I've tried this:</p>

<pre><code>---
output: 
  html_document: 
    fig_height: 8
    fig_width: 10
    df_print: paged
    rows.print: 25
---
</code></pre>

<p>which doesn't work (still at default 10 rows), and this:</p>

<pre><code>```{r}
knitr::opts_chunk$set(echo = FALSE, rows.print=25)
cars
```
</code></pre>

<p>which also doesn't work.</p>