title: change the specific cell value having common index in pandas
body: <p>I am trying to change the value of particular cell of pandas Dataframe.  using <code>loc</code> i am finding all the column having the given index and then trying to change the given row and column value, but it is not reflecting in the original dataframe.</p>
  
  <pre><code>df.loc[df.index == 'Lactose intolerance ', 'abdominal pain'] = "yes"
  </code></pre>
  
  <p>result is :</p>
  
  <p>Diagnosis </p>
  
  <p>Lactose intolerance     yes </p>
  
  <p>Lactose intolerance     yes</p>
  
  <p>Name: abdominal pain, dtype: object</p>
  
  <p>but when try to do for only one row it's not changing that cell value.</p>
  
  <pre><code>df.loc[df.index == 'Lactose intolerance ', 'abdominal pain'].iloc[0] = "no"
  </code></pre>
  
  <p>now the cell value is not changed. why is it happening so?</p>