title: How can I add vertical lines and horizontal text out of the plot axis limits in ggplot2/R?
body: <p>I have a barplot made primarily in ggplot2. I want two vertical lines added and some text below the x-axis. </p>
  
  <pre><code>#Load data
  d &lt;- structure(list(author = structure(c(1L, 2L, 4L, 3L, 5L, 6L, 8L, 11L, 13L, 12L, 10L, 9L, 7L), .Label = c("Bahr et al", "Fuller et al", "Garbossa et al", "Gokhale et al", "Iuchi et al", "Lee et al", "Lee Y et all", "Merrel et al", "Newton et al", "Rossetti et al", "Usery et al", "Wychowski et al", "Zachenhofer et al"), class = "factor"), nAE = c(-22L, -34L, -158L, -90L, -70L, -41L, -48L, -32L, -73L, -23L, -25L, -13L, -46L), AE = c(3L, 1L, 7L, 1L, 3L, 10L, 3L, 6L, 3L, 5L, 4L, 6L, 5L), SAE = c(0L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 2L, 0L, 2L, 0L, 0L)), .Names = c("author", "nAE", "AE", "SAE"), class = "data.frame", row.names = c(NA, -13L))
  </code></pre>
  
  <p>Code to my barplot:</p>
  
  <pre><code>library(dplyr)
  library(tidyr)
  library(ggplot2)
  
  categories &lt;- c("Adverse Effect", "No adverse effects", "Severe side effects")
  cols &lt;- c("#f6766d", "#01bfc4", "orange")
  
  
  q &lt;- d %&gt;% 
  gather(key, value, -author) %&gt;% 
  ggplot(aes(author, value, fill = key)) +
  geom_col(alpha=0.9) + 
  scale_x_discrete(name="Author") +
  scale_y_continuous(name="Number of observations", limits=c(-160,15), 
  seq(-160, 15, by=10)) +
  theme_grey() +
  theme(legend.position = "top") +
  scale_fill_manual(labels = categories, values = cols) + 
  labs(fill = "")
  </code></pre>
  
  <p>I have attached a picture below of how I want my barplot to look like. As you can see, I have added two vertical lines (at random position) and three texts (in photoshop).</p>
  
  <p><a href="https://i.stack.imgur.com/vTX3p.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vTX3p.png" alt="enter image description here"></a></p>
  
  <p>Thanks in advance,
  C.</p>