title: Numbers used as string in Pandas index
body: <p>I have the following file:</p>
  
  <pre><code>Contract, FG
  9896342,Y
  11037874,Y
  6912529,Y
  9896652,N
  363291,Y
  7348524,Y
  6078482,Y
  7795457,N
  2486242,Y
  3297980,Y
  9760560,Y
  1200533,N
  11033963,N
  7861603,Y
  8218268,Y
  9760247,Y
  </code></pre>
  
  <p>I would like to create from this file an pandas DF and to use the column Contract as a string or unicode index column. It looks like number, but technically, it is a string. </p>
  
  <p>I did this: <code>DF = pd.read_csv('C:\\Users\\S.Benet\\Desktop\\test.txt', index_col='Contract', dtype=object, encoding = 'utf-8')</code></p>
  
  <p>But the index is interpreted as INT. </p>
  
  <pre><code>&gt;&gt;DF.index
  Int64Index([ 9896342, 11037874,  6912529,  9896652,   363291,  7348524,
               6078482,  7795457,  2486242,  3297980,  9760560,  1200533,
              11033963,  7861603,  8218268,  9760247],
             dtype='int64', name=u'Contract')
  </code></pre>
  
  <p>How can I force it to be a string index?</p>