title: Combine odd and even indexed rows in pandas
body: <p>I have a data frame <code>df</code> like this,</p>
  
  <pre><code>   Name     Net        Quantity  
  0  Auto     1010       10
  1  NaN      NaN        12
  2  Rtal     4145       18
  3  NaN      NaN        14
  4  Indl     6223       16
  5  NaN      7222       18
  </code></pre>
  
  <p>My output data frame should be like this,</p>
  
  <pre><code>       Name     Net         Quantity  
      0  Auto     1010        10,12
      1  Rtal     4145        18,14
      2  Indl     6223,7222   16,18
  </code></pre>
  
  <p>As you can see from above data frame, I want to combine values with even number (index) of rows if there is any values present in odd number (index) so that I can get my output.</p>
  
  <p>I tried the following to extract odd number values,</p>
  
  <pre><code>df.iloc[1::2, :]
  </code></pre>
  
  <p>this gives me the following,</p>
  
  <pre><code>    Name    Net   Quantity
  1   NaN     NaN       12
  3   NaN     NaN       14
  5   NaN     7222.0    18
  </code></pre>
  
  <p>after this, I don't now how to add these values to even number indexes to my <code>df</code>. In addition to this, I am not sure if my approach is correct. I would appreciate if anyone could advise/help.</p>