title: How can I plot multiple variables side-by-side in a dotplot in R?
body: <p>I'm still pretty new to R, and have come up against a plotting problem I can't find an answer to.  </p>
  
  <p>I've got a data frame that looks like this (though a lot bigger):</p>
  
  <pre><code>df &lt;- data.frame(Treatment= rep(c("A", "B", "C"), each = 6),
                   LocA=sample(1:100, 18), 
                   LocB=sample(1:100, 18), 
                   LocC=sample(1:100, 18))
  </code></pre>
  
  <p>And I want dot plots that look like <a href="http://www.flickr.com/photos/65916813@N02/" rel="noreferrer">this one</a> produced in Excel.  It's exactly the formatting I want:  a dotplot for each of the treatments side-by-side for each location, with data for multiple locations together on one graph. (Profuse apologies for not being able to post the image here; posting images requires a 10 reputation.)</p>
  
  <p><img src="https://i.stack.imgur.com/BfE1d.png" alt="enter image description here"></p>
  
  <p>It's no problem to make a plot for each location, with the dots color-coded, and so on:</p>
  
  <pre><code>ggplot(data = df, aes(x=Treatment, y=LocA, color = Treatment)) + geom_point() 
  </code></pre>
  
  <p>but I can't figure out how to add locations B and C to the same graph.  </p>
  
  <p>Any advice would be much appreciated!</p>