title: R: handling and plotting grouped data
body: <p>This is a follow up question on this one: <a href="https://stackoverflow.com/questions/17150183/r-plot-multiple-lines-in-one-graph">R: plot multiple lines in one graph</a></p>
  
  <p>In there I used part of my data to graph 1 graph with multiple lines. Now I want to graph multiple graphs in one grid, since I have grouped data. 
  Right now I'm doing this with creating dataframes for each group of data and then creating a graph for each dataframe and combine those using <code>gridd.arrange()</code> 
  However, I'm wondering if I could handle the grouped data as 1 dataset instead of creating all those separate tables?</p>
  
  <p>The data I have is structured like this:</p>
  
  <pre><code>          Category1    Category2    Category3
  Company   2011   2013  2011   2013  2011   2013
  Company1  300    350   290    300   295    290
  Company2  320    430   305    301   300    400
  Company3  310    420   400    305   400    410
  </code></pre>
  
  <p>So is there any way to proces this at once and plot the 3 graphs (for each Category) with lines for each Company for the Year (2011 and 2013)?</p>