title: How to plot datetime time with matplotlib?
body: <p>I have the following pandas dataframe</p>
  <pre class="lang-py prettyprint-override"><code>import pandas as pd
  import matplotlib.pyplot as plt
  from datetime import datetime
  import time
  
  data = {'date': ['09:50:00', '09:55:00', '10:00:00', '10:05:00', '10:10:00', '10:15:00', '10:20:00', '10:25:00', '10:30:00', '10:35:00'],
          'bidopen': [1.33872, 1.33824, 1.33768, 1.33732, 1.33786, 1.33798, 1.33752, 1.33749, 1.33718, 1.3374],
          'bidclose': [1.33824, 1.33768, 1.33732, 1.33786, 1.33798, 1.33752, 1.33749, 1.33718, 1.3374, 1.33766],
          'bidhigh': [1.33889, 1.33832, 1.33774, 1.33786, 1.33814, 1.33815, 1.33776, 1.33781, 1.33765, 1.33769],
          'bidlow': [1.33822, 1.33766, 1.33716, 1.33725, 1.3378, 1.33747, 1.33742, 1.33712, 1.33714, 1.33729],
          'askopen': [1.33891, 1.33842, 1.33787, 1.33751, 1.33803, 1.33816, 1.33768, 1.3377, 1.33735, 1.3376],
          'askclose': [1.33842, 1.33787, 1.33751, 1.33803, 1.33816, 1.33768, 1.3377, 1.33735, 1.3376, 1.33785],
          'askhigh': [1.33908, 1.3385, 1.33793, 1.33804, 1.33832, 1.33834, 1.33795, 1.338, 1.33782, 1.33787],
          'asklow': [1.33838, 1.33784, 1.33734, 1.33743, 1.33799, 1.33765, 1.33762, 1.33728, 1.33733, 1.33749],
          'tickqty': [875, 818, 886, 600, 704, 837, 947, 1010, 1178, 567]}
  
  df = pd.DataFrame(data)
  
  df['date'] = pd.to_datetime(df['date'])
  df['date'] = df['date'].dt.time
  
  print(df.head(10).to_string())
  
  plt.plot(df['date'], df['bidhigh'])
  plt.show()
  </code></pre>
  <p>I am unable to plot the time column on the x-axis and the <code>bidghigh</code> column on the y-axis. I get this error:</p>
  <pre><code>Traceback (most recent call last):
  
    File &quot;&lt;ipython-input-55-3572052619ce&gt;&quot;, line 1, in &lt;module&gt;
  plt.plot(x, y)
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/pyplot.py&quot;, line 2825, in plot
  **({&quot;data&quot;: data} if data is not None else {}), **kwargs)
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/axes/_axes.py&quot;, line 1745, in plot
  self.add_line(line)
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/axes/_base.py&quot;, line 1969, in add_line
  self._update_line_limits(line)
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/axes/_base.py&quot;, line 1991, in _update_line_limits
  path = line.get_path()
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/lines.py&quot;, line 1011, in get_path
  self.recache()
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/lines.py&quot;, line 653, in recache
  x = _to_unmasked_float_array(xconv).ravel()
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/matplotlib/cbook/__init__.py&quot;, line 1289, in _to_unmasked_float_array
  return np.asarray(x, float)
  
    File &quot;/home/mahmoud/anaconda3/envs/fxenv/lib/python3.7/site-packages/numpy/core/_asarray.py&quot;, line 85, in asarray
  return array(a, dtype, copy=False, order=order)
  
  TypeError: float() argument must be a string or a number, not 'datetime.time'
  </code></pre>
  <p>My question is: how do I plot the date column on the x-axis and the <code>bidhigh</code> column on the y-axis?</p>