title: .apply() throwing TypeError: object of type 'float' has no len()
body: <p>I'm trying to get length of my fields in <code>item_description</code> column and store into new column, but it throws this error <code>TypeError: object of type 'float' has no len()</code></p>
  
  <p>Code:</p>
  
  <pre><code>df['desc_len']=df['item_description'].apply(len)
  </code></pre>
  
  <p>When I run it on <code>name</code> field (<code>dtype</code> for both is <code>object</code>) it runs without error.
  What am I missing?</p>
  
  <p><code>df</code> is a DataFrame</p>