title: How could I detect subtypes in pandas object columns?
body: <p>I have the next DataFrame:</p>
  
  <pre><code>df = pd.DataFrame({'a': [100, 3,4], 'b': [20.1, 2.3,45.3], 'c': [datetime.time(23,52), 30,1.00]})
  </code></pre>
  
  <p>and I would like to <em>detect <strong>subtypes</strong></em> in columns without explicit programming a loop, if possible.</p>
  
  <p>I am looking for the next output:</p>
  
  <pre><code>column a = [int]
  column b = [float]
  column c = [datetime.time, int, float]
  </code></pre>