title: what's the difference between set_value and = in pandas
body: <p>In writing to a dataframe in <code>pandas</code>, we see we have a couple of ways to do it, as provided by <a href="https://stackoverflow.com/questions/13842088/set-value-for-particular-cell-in-pandas-dataframe">this answer</a> and <a href="https://stackoverflow.com/questions/17729853/set-value-for-a-selected-cell-in-pandas-dataframe">this answer</a>. </p>
  
  <p>We have the method of </p>
  
  <ul>
  <li><code>df[r][c].set_value(r,c,some_value)</code> and the method of </li>
  <li><code>df.iloc[r][c] = some_value</code>. </li>
  </ul>
  
  <p>What is the difference? Which is faster? Is either a copy?</p>