title: Editing legend labels in ggplot
body: <p>I have a dataframe that looks like this:</p>
  <pre><code>data
      median  min max no_of_threads
      2.33    2.10    6.85    1
      2.43    2.14    3.41    2
      2.39    2.13    7.90    3
      2.74    2.10    8.30    4
      2.53    2.21    6.69    5
  </code></pre>
  <p>I made this R function, that plots data$min and data$max as range, and data$median as line:</p>
  <pre><code>scalability_graph &lt;- function(data){ 
    h &lt;- ggplot(data)
    h &lt;- h + 
        geom_ribbon(aes(x = no_of_threads, ymin = min, ymax = max)) +
        geom_line(aes(x = no_of_threads, y=median, color=&quot;#CC873D&quot;)) +
        scale_x_continuous(&quot;Number of threads&quot;, lim=c(0,20)) +
        scale_y_continuous(&quot;Response time&quot;, lim=c(0,13)) +
        opts(legend.position=c(0.20,0.90))
  }
  </code></pre>
  <p>The script produces this plot:</p>
  <p><img src="https://i.stack.imgur.com/whBg6.png" alt="range graph with median" /></p>
  <p>How to change labels in legend and put &quot;range&quot; instead of top bold string, and &quot;median&quot; instead of bottom label?</p>