title: color and change line type in a ggplot by group
body: <p>I have a dataframe so far as follows:</p>
  <pre><code>  N Method1-Simulation Method1-Analytical Method2-Simulation Method3-Analytical
  1 2              0.094          0.1831891              0.158          0.2789826
  2 3              0.236          0.2856285              0.434          0.4670031
  3 4              0.349          0.3740548              0.568          0.6097311
  4 5              0.450          0.4525999              0.682          0.7174169
  5 6              0.506          0.5228121              0.781          0.7976934
  6 7              0.585          0.5854665              0.851          0.8566850
  </code></pre>
  <p>It will grow to accommodate more methods. I want to make a ggplot where each method has it's own color and the analytical method is a solid line while the simulation method is a broken line.</p>
  <p>I have everything but the broken line as follows:</p>
  <pre><code>longPowerCurve &lt;- melt(powerCurve, id = &quot;N&quot;)
  colnames(longPowerCurve)[2] &lt;- &quot;Method&quot;
  
  ggplot(data=longPowerCurve,aes(x=N, y=value, colour=Method)) + geom_line() +ylab(&quot;Power&quot;) +ggtitle(&quot;Power levels for various N and distributions&quot;)+
    theme(legend.text = element_text(size = 12))
  </code></pre>
  <p>Is there a way I can automate this so that if I have 5, 6,7,8, etc methods, it all still works?</p>