title: ValueError: could not convert string to float: '2019-01-01 00:00:00' in Python 3D graph
body: <p>I am trying to plot a 3D graph with date as x-value, temperature as y-value and total energy consumed as z-value. Here is my code:</p>
  <pre><code>import matplotlib.pyplot as plt
  import pandas as pd
  
  df = pd.read_csv('floor2.csv')
  
  td = plt.figure().gca(projection='3d')
  
  td.scatter(df['Date'], df['T_out'].values, df['Total'].values)
  td.set_xlabel('Date')
  td.set_ylabel('Outdoor Temperature')
  td.set_zlabel('Total Consumed Energy')
  plt.show()
  </code></pre>
  <p>However, I am getting the following error for date value:</p>
  <pre><code>ValueError: could not convert string to float: '2019-01-01 00:00:00'
  </code></pre>
  <p>Any help, please. Thank you...</p>