title: Pandas multiple bar charts with 2 columns on X-axis
body: <p>I'm trying to make an array of bar charts, one chart per city with each chart displaying the counts on the Y-Axis (ranging 70 - 210) and on the X-axis I'd like to have 21 bars, one for each weekday AND time slot combination (7x3=21). This is the data</p>
  
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  
  data = [
      ['CITY','DAY','TIME_BIN', 'COUNT'],
      ['PHOENIX', "Friday", 1, 70],
      ['PHOENIX', "Thursday", 2, 80],
      ['PHOENIX', "Wednesday", 3, 90],
      ['ATLANTA', "Sunday", 1, 130],
      ['ATLANTA', "Monday", 2, 150],
      ['ATLANTA', "Tuesday", 3, 160],
      ['CHICAGO', "Saturday", 1, 180],
      ['CHICAGO', "Friday", 2, 200],
      ['CHICAGO', "Friday", 3, 210],
  ]
  df = pd.DataFrame(data[1:],columns=data[0])
  print(df)
  
            CITY        DAY  TIME_BIN  COUNT
  0  PHOENIX     Friday         1     70
  1  PHOENIX   Thursday         2     80
  2  PHOENIX  Wednesday         3     90
  3  ATLANTA     Sunday         1    130
  4  ATLANTA     Monday         2    150
  5  ATLANTA    Tuesday         3    160
  6  CHICAGO   Saturday         1    180
  7  CHICAGO     Friday         2    200
  8  CHICAGO     Friday         3    210
  </code></pre>
  
  <p>I want the output to be some combination of the two attempts below. Combine the array functionality but with bar charts. </p>
  
  <pre><code># Successful attempt at making an array of charts but wrong type 
  df[['DAY', 'TIME_BIN']].hist(by=df['CITY'])
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/80msj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/80msj.png" alt="enter image description here"></a></p>
  
  <pre><code># Bar chart with proper counts but x-axis did not combine properly
  ax = df.plot(x=['DAY', 'TIME_BIN'],
                                                         y='COUNT',
                                                         kind='bar',
                                                         color=["g","b"])
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/yePJN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yePJN.png" alt="enter image description here"></a></p>