title: reading sparse csv file into pandas
body: <p>I have a space separated CSV file in following format:</p>
  
  <pre><code>2012-11-01 1 2012-12-01 4 2013-02-01 6
  2012-12-01 2 2013-01-01 nan
  2012-11-01 3 2012-12-01 5 2013-01-01 5 2013-04-01 7
  </code></pre>
  
  <p>basically dates followed by a value, but the dates are sparse. Some of the values are nan, or also could be missing. I would like to be able to read this into Pandas and line up the values based on the corresponding dates.</p>
  
  <p>Running Pandas:</p>
  
  <pre><code>import pandas as pd
  pd.read_csv('sparse.csv', sep=" ", parse_dates=True)
  </code></pre>
  
  <p>errors with:</p>
  
  <pre><code>ValueError: Expecting 6 columns, got 8 in row 1
  </code></pre>
  
  <p>What would be a way to read this file and align the date/values?</p>
  
  <p>(Is there some "pre-processing" I could do maybe?)</p>
  
  <p>Thanks</p>