title: ggplot - change line width
body: <p>I can plot each series in a different colour in ggplot2 by doing something like this ...</p>
  
  <pre><code>colours &lt;- c('red', 'blue')
  p &lt;- ggplot(data=m, mapping=aes_string(x='Date', y='value'))
  p &lt;- p + geom_line(mapping=aes_string(group='variable', colour='variable'), size=0.8)
  p &lt;- p + scale_colour_manual(values=colours)
  </code></pre>
  
  <p>Is there something comparable I can do to set different line widths for each series? (Ie. I want to use a thick red line to plot the trend and a thin blue line to plot the seasonally adjusted series.)</p>