title: How to draw the boxplot with significant level?
body: <p>Some time ago I asked a question about drawing boxplot <a href="https://stackoverflow.com/questions/14604439/plot-multiple-boxplot-in-one-graph">Link1</a>.</p>
  
  <p>I have got some data with 3 different groups (or labels) <a href="http://ge.tt/4vn9GwC2/v/0?c" rel="noreferrer">Please down load here</a>. I can use the following R codes to get the boxplot</p>
  
  <pre><code>library(reshape2)
  library(ggplot2)
  
  morphData &lt;- read.table(".\\TestData3.csv", sep=",", header=TRUE);
  morphData.reshaped &lt;- melt(morphData, id.var = "Label")
  
  ggplot(data = morphData.reshaped, aes(x=variable, y=value)) + 
    + geom_boxplot(aes(fill=Label))
  </code></pre>
  
  <p>Here I just wondering how to put the significant level above the boxplot. To make myself clear I put a screenshot cut from a paper here:</p>
  
  <p><img src="https://i.stack.imgur.com/WkSLc.png" alt="Boxplot"></p>