title: Pandas how can 'replace' work after 'loc'?
body: <p>I have tried many times, but seems the 'replace' can NOT work well after use 'loc'.
  For example I want to replace the 'conlumn_b' with an regex for the row that the 'conlumn_a' value is 'apple'.</p>
  
  <p>Here is my sample code : </p>
  
  <pre><code>df.loc[df['conlumn_a'] == 'apple', 'conlumn_b'].replace(r'^11*', 'XXX',inplace=True, regex=True)
  </code></pre>
  
  <p>Example:</p>
  
  <pre><code>conlumn_a       conlumn_b
  apple           123
  banana          11
  apple           11
  orange          33
  </code></pre>
  
  <p>The result that I expected for the 'df' is:</p>
  
  <pre><code>conlumn_a       conlumn_b
  apple           123
  banana          11
  apple           XXX
  orange          33
  </code></pre>
  
  <p>Anyone has meet this issue that needs 'replace' with regex after 'loc' ? </p>
  
  <p>OR you guys has some other good solutions ?</p>
  
  <p>Thank you so much for your help!</p>