title: How to filter a list column in a dataframe?
body: <p>I have a data frame like this:</p>
  <pre><code>df:
  ID    Names
  3    [Ally, Ben, Cris]
  5    [Bruno, Coleen, Flyn]
  2    [Dave, Bob]
  7    [Rob, Ally, Bob]
  11   [Jill, Tom, Sal]
  </code></pre>
  <p>The Names column is a list of names. Some of them could be repeated.</p>
  <p>I want to filter the data frame on Names columns where the names start with either A or B or D.</p>
  <p>So my output should look like this:</p>
  <pre><code>ID    Names
  3    [Ally, Ben]
  5    [Bruno]
  2    [Dave, Bob]
  7    [Ally, Bob]
  </code></pre>
  <p>Reproducible input:</p>
  <pre><code>df = pd.DataFrame({'ID': [3, 5, 2, 7, 11],
                     'Names': [['Ally', 'Ben', 'Cris'],
                               ['Bruno', 'Coleen', 'Flyn'],
                               ['Dave', 'Bob'],
                               ['Rob', 'Ally', 'Bob'],
                               ['Jill', 'Tom', 'Sal']]
                    })
  </code></pre>