title: Python Pandas - Reshape Dataframe
body: <p>Given the following data frame:</p>
  
  <pre><code>pd.DataFrame({"A":[1,2,3],"B":[4,5,6],"C":[6,7,8]})
  
     A   B   C
  0  1   4   6
  1  2   5   7
  2  3   6   8
  3  11  14  16
  4  12  15  17
  5  13  16  18
  </code></pre>
  
  <p>I would like to reshape it so it would look like so:</p>
  
  <pre><code>   A   B   C   A_1   B_1   C_1   A_2   B_2   C_2
  0  1   4   6     2     5     7     3     6     8
  1  11  14  16    12    15    17    13    16    18
  </code></pre>
  
  <p>So every 3 rows are grouped into 1 row</p>
  
  <p>How can I achieve this with pandas?</p>