title: Plotting a grouped bar chart from two Excel sheets with a primary key?
body: <p>I have two Excel sheets as follows:</p>
  
  <p><a href="https://i.stack.imgur.com/1fqYp.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1fqYp.jpg" alt="Sheet1"></a></p>
  
  <p><a href="https://i.stack.imgur.com/1fqYp.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ci9py.jpg" alt="ٍSheet2"></a></p>
  
  <p>I need to plot the count of each <code>Grade</code> (A, B, C,..) in every <code>Region</code> (Region1, Region2,..) in a grouped bar chart.</p>
  
  <p>I loaded the two sheets using pandas as follows:</p>
  
  <pre><code>xl = pd.ExcelFile("D:/Works.xlsx")
  df = xl.parse("Sheet1")
  ds = xl.parse("Sheet2")
  </code></pre>
  
  <p>Then I merged the sheets in one dataframe:</p>
  
  <pre><code>data_set = pd.merge(df, ds, how='left')
  </code></pre>
  
  <p>The DataFrame <code>data_set</code> is replicated as:</p>
  
  <pre><code>data_set = pd.DataFrame({'Center_ID': ['E25007','E08003','E17020','E08004','E25007','E08035','E08614','E08026','E25023','E17006','E25007','E08004'],
   'Grade': ['A', 'B', 'B', 'A', 'C', 'F', 'A', 'A', 'E', 'F', 'C', 'B'],
   'Name': ['Jack','Eliana','Frank','Sheila','Irene','Celine','Sebastian','Teun','Silvia','Luis','Catalina','Patricia'],
   'Region': ['Region1',None,'Region4','Region3','Region1','Region2','Region2','Region3','Region3','Region2','Region1','Region3'],
   'Sector': ['Sector1',None,'Sector1','Sector3','Sector1','Sector1','Sector3','Sector2','Sector1','Sector2','Sector1','Sector3']})
  </code></pre>
  
  <p>What can I do next in order to create the grouped Bar chart?</p>