title: Load CSV to Pandas MultiIndex DataFrame
body: <p>I have a 719mb CSV file that looks like:</p>
  
  <pre><code>from, to, dep, freq, arr, code, mode   (header row)
  RGBOXFD,RGBPADTON,127,0,27,99999,2
  RGBOXFD,RGBPADTON,127,0,33,99999,2
  RGBOXFD,RGBRDLEY,127,0,1425,99999,2
  RGBOXFD,RGBCHOLSEY,127,0,52,99999,2
  RGBOXFD,RGBMDNHEAD,127,0,91,99999,2
  RGBDIDCOTP,RGBPADTON,127,0,46,99999,2
  RGBDIDCOTP,RGBPADTON,127,0,3,99999,2
  RGBDIDCOTP,RGBCHOLSEY,127,0,61,99999,2
  RGBDIDCOTP,RGBRDLEY,127,0,1430,99999,2
  RGBDIDCOTP,RGBPADTON,127,0,115,99999,2
  and so on... 
  </code></pre>
  
  <p>I want to load in to a pandas DataFrame. Now I know there is a load from csv method:</p>
  
  <pre><code> r = pd.DataFrame.from_csv('test_data2.csv')
  </code></pre>
  
  <p>But I specifically want to load it as a 'MultiIndex' DataFrame where from and to are the indexes:</p>
  
  <p>So ending up with:</p>
  
  <pre><code>                   dep, freq, arr, code, mode
  RGBOXFD RGBPADTON  127     0   27  99999    2
          RGBRDLEY   127     0   33  99999    2
          RGBCHOLSEY 127     0 1425  99999    2
          RGBMDNHEAD 127     0 1525  99999    2
  </code></pre>
  
  <p>etc. I'm not sure how to do that?</p>