title: Replacing values in pandas data frame with None
body: <p>This thread <a href="https://stackoverflow.com/questions/27060098/replacing-few-values-in-a-pandas-dataframe-column-with-another-value">here</a> shows <code>replace</code> with <code>inplace=True</code> to change values in pandas data frame.</p>
  <p>I want to apply the same technique, but replacing with <code>None</code></p>
  <pre><code>mydf = pd.DataFrame({&quot;col1&quot;:[5, 5, 8, 4, 5], &quot;col2&quot;:[2, 5, 6, 7, 5]})
  mydf.replace([5], None, inplace=True)
  </code></pre>
  <p><code>mydf</code> changes like this and there is an additional output</p>
  <pre><code>   col1  col2
  0     5     2
  1     5     2
  2     8     6
  3     4     7
  4     4     7
  </code></pre>
  <pre><code>col1    None
  col2    None
  dtype: object
  </code></pre>
  <p>How to replace values with <code>None</code>?</p>