title: Need to transpose a pandas dataframe
body: <p>I have a Series that look like this: </p>
  
  <pre><code>      col1          id
   0      a           10
   1      b           20
   2      c           30
   3      b           10
   4      d           10
   5      a           30
   6      e           40
  </code></pre>
  
  <p>My desired output is this: </p>
  
  <pre><code>    a   b   c   d   e
  10  1   1   0   1   0
  20  0   1   0   0   0
  30  1   0   1   0   0
  40  0   0   0   0   1
  </code></pre>
  
  <p>I got this code: </p>
  
  <pre><code>import pandas as pd
  
  df['dummies'] = 1
  df_ind.pivot(index='id', columns='col1', values='dummies') 
  </code></pre>
  
  <p>I get an error: </p>
  
  <pre><code>    137 
      138         if mask.sum() &lt; len(self.index):
  --&gt; 139             raise ValueError('Index contains duplicate entries, '
      140                              'cannot reshape')
      141 
  
  ValueError: Index contains duplicate entries, cannot reshape
  </code></pre>
  
  <p>There are duplicate id's because multiple values in col1 can be attributed to a single id. </p>
  
  <p>How can I achieve the desired output? </p>
  
  <p>Thanks!</p>