title: Control alignment of two side-by-side plots in knitr
body: <p>I cannot figure out how to arrange two side-by-side plots as explained in the knitr graphics manual page 2 (<a href="http://yihui.name/knitr/demo/graphics/" rel="noreferrer">http://yihui.name/knitr/demo/graphics/</a>). I use the following MWE and the output is below. I would like them to be aligned as shown in the manual for the two cars plots (also on page 2 of the manual). The pdf is generated in RStudio (Knit to PDF).</p>
  
  <pre><code>---
  title: "Untitled"
  output: pdf_document
  ---
  
  ## R Markdown
  
  ```{r,echo=FALSE,out.width='.49\\linewidth', fig.width=3, fig.height=3}
  
  barplot(1:4)
  barplot(4:7)
  
  ```
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/CzPWG.png" rel="noreferrer"><img src="https://i.stack.imgur.com/CzPWG.png" alt="enter image description here"></a></p>