title: how to ad a vertical line to matplotlib?
body: <p>I want to show a vertical line at x='23:30:00'. I have tried x = '23:30' as well. Any ideas?</p>
  
  <pre><code>df1 = df1.between_time('19:30','23:59')
  df1['high'].plot(kind='line',figsize = (10,5))
  plt.axvline(x='23:30:00', color = 'r')
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/vaU9v.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vaU9v.png" alt="Add vert line to chart at 23:30"></a></p>