title: How to display really tall ggplot?
body: <p>For example, while trying to display a facetted plot with one hundred rows:</p>
  
  <pre><code>library(ggplot2)
  set.seed(111)
  tmp_d &lt;- data.frame(group = rep(1:100, each = 5), 
                      x = rep(1:5, times = 100),
                      y = runif(1:500))
  ## looks like
  #   group x         y
  # 1     1 1 0.5929813
  # 2     1 2 0.7264811
  # 3     1 3 0.3704220
  # 4     1 4 0.5149238
  # 5     1 5 0.3776632
  # 6     2 1 0.4183373
  # ...
  
  ggplot(tmp_d, aes(x,y)) +
      geom_point() +
      facet_wrap(~ group, ncol = 1)
  </code></pre>
  
  <p>I get a mess in the plotting window in Rstudio which I cannot zoom into or scroll:</p>
  
  <p><a href="https://i.stack.imgur.com/KUSpW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KUSpW.png" alt="enter image description here"></a></p>
  
  <p>Inconvenient work-arounds involve <code>ggsave</code> or <code>knitr</code>:</p>
  
  <h3>Using <code>ggsave</code>:</h3>
  
  <pre><code>ggsave('tmp_20170104_long_ggplot.png', p, height = 100, limitsize = F)
  </code></pre>
  
  <h3>Using <code>knitr</code>:</h3>
  
  <p>Embed the plot in a <code>knitr</code> code chunk with a large arbitrary value for <code>fig.height</code>:</p>
  
  <pre><code>---
  title: "Test plot of tall ggplot2"
  
  output:
      html_document
  ---
  
  ```{r, fig.height = 100}
  library(ggplot2)
  set.seed(111)
  tmp_d &lt;- data.frame(group = rep(1:100, each = 5), 
                      x = rep(1:5, times = 100),
                      y = runif(1:500))
  
  ggplot(tmp_d, aes(x,y)) +
      geom_point() +
      facet_wrap(~ group, ncol = 1)
  ```
  </code></pre>
  
  <h3>Two questions:</h3>
  
  <ol>
  <li>How do I easily display such plots?</li>
  <li>How do I determine what the height value has to be for each of the work-arounds?</li>
  </ol>