title: Python Pandas: how to overwrite subset of a dataframe with a subset of another dataframe?
body: <p>Given <code>df1</code> and <code>df2</code>, how do I get <code>df3</code> using pandas, where <code>df3</code> has <code>df1</code> elements: </p>
  
  <pre><code>[11, 12, 21, 22]
  </code></pre>
  
  <p>in the place of <code>df2</code> elements</p>
  
  <pre><code>[22, 23, 32, 33]
  </code></pre>
  
  <p>Condition: indexes of row 1 &amp; 2 in <code>df1</code> are the same as indexes of row 2  &amp; 3 in <code>df2</code></p>