title: How to I replace NULL with 0
body: <p>I trying to replace NULL values to zero.</p>
  
  <p>Using <code>rf['Pt 1']=rf['Pt 1'].fillna(0,inplace=True)</code> only helps to replace blank with 0.</p>
  
  <p>But I still did not manage to replace <code>NULL</code> (i.e. the string <code>"Null"</code>, not a <code>None</code> value) with zero.</p>
  
  <p>Anyone know how to go about replacing NULL with 0 ? </p>
  
  <pre><code>rf['Pt 1']=rf['Pt 1'].fillna(0,inplace=True)
  </code></pre>
  
  <p>My output result: </p>
  
  <pre><code>    Pt 1
      0
      NULL
      990
      991
      996
      995
      992
      992
      992
      993
      993
      993
      991
      991
      989
      NULL
      NULL
      NULL
      995
      993
  </code></pre>