title: rmarkdown - grid layout
body: <p>How can one set up a grid layout in <code>rmarkdown</code> please?  </p>
  
  <p>In the .rmd script below, I have tried having rows, following <a href="http://rmarkdown.rstudio.com/flexdashboard/" rel="nofollow noreferrer">this <code>flexdashboard</code> example</a>. But it does not work: the charts/tables appear one below the other in the pdf.  </p>
  
  <p><strong>Snippet:</strong></p>
  
  <pre><code>---
  title: "Row Orientation"
  output: pdf_document
  orientation: rows
  classoption: landscape
  ---
  Row
  -------------------------------------
  ### Chart 1
  ```{r}
  hist(AirPassengers)
  ```
  Row
  -------------------------------------
  ### Chart 2
  ```{r}
  head(mtcars)
  ```
  ### Chart 3
  ```{r}
  hist(AirPassengers)
  ```
  </code></pre>
  
  <p>What do you think is wrong with this code please?</p>