title: How can I create column from dictionary keys in same dataframe?
body: <p>I have a dataframe, something like:</p>
  <pre><code>|   | a | b                |
  |---|---|------------------|
  | 0 | a | {'d': 1, 'e': 2} |
  | 1 | b | {'d': 3, 'e': 4} |
  | 2 | c | NaN              |
  | 3 | d | {'f': 5}         |
  </code></pre>
  <p>How can make something like this:</p>
  <pre><code>|   | a | b                | d | e | f |
  |---|---|------------------|---|---|---|
  | 0 | a | {'d': 1, 'e': 2} | 1 | 2 |nan|
  | 1 | b | {'d': 3, 'e': 4} | 3 | 4 |nan|
  | 2 | c | NaN              |nan|nan|nan|
  | 3 | d | {'f': 5}         |nan|nan| 5 |
  </code></pre>
  <p><br>I tried doing this <a href="https://stackoverflow.com/questions/38231591/split-explode-a-column-of-dictionaries-into-separate-columns-with-pandas">Split / Explode a column of dictionaries into separate columns with pandas</a> but due to null values present, it is throwing an error.
  <br> <strong>'float' object has no attribute 'items'</strong> </p>