title: Sum of a Column in a Dictionary of Dataframes
body: <p>How can I work with a dictionary of dataframes please? Or, is there a better way to get an overview of my data? If I have for example:</p>
  
  <pre><code>Fruit   Qty Year
  Apple   2   2016
  Orange  1   2017
  Mango   2   2016
  Apple   9   2016
  Orange  8   2015
  Mango   7   2016
  Apple   6   2016
  Orange  5   2017
  Mango   4   2015
  </code></pre>
  
  <p>Then I am trying to find out how many in total I get per year, for example:</p>
  
  <pre><code>        2015    2016    2017
  Apple   0       11      0
  Orange  8       0       6
  Mango   4       9       0
  </code></pre>
  
  <p>I have written some code but it might not be useful:</p>
  
  <pre><code>import pandas as pd
  
  # Fruit Data
  df_1 = pd.DataFrame({'Fruit':['Apple','Orange','Mango','Apple','Orange','Mango','Apple','Orange','Mango'], 'Qty': [2,1,2,9,8,7,6,5,4], 'Year': [2016,2017,2016,2016,2015,2016,2016,2017,2015]})
  
  # Create a list of Fruits
  Fruits = df_1.Fruit.unique()
  
  # Break down the dataframe by Year
  df_2015 = df_1[df_1['Year'] == 2015]
  df_2016 = df_1[df_1['Year'] == 2016]
  df_2017 = df_1[df_1['Year'] == 2017]
  
  # Create a dataframe dictionary of Fruits
  Dict_2015 = {elem : pd.DataFrame for elem in Fruits}
  Dict_2016 = {elem : pd.DataFrame for elem in Fruits}
  Dict_2017 = {elem : pd.DataFrame for elem in Fruits}
  
  # Store the Qty for each Fruit x each Year
  for Fruit in Dict_2015.keys():
      Dict_2015[Fruit] = df_2015[:][df_2015.Fruit == Fruit]
  for Fruit in Dict_2016.keys():
      Dict_2016[Fruit] = df_2016[:][df_2016.Fruit == Fruit]
  for Fruit in Dict_2017.keys():
      Dict_2017[Fruit] = df_2017[:][df_2017.Fruit == Fruit]
  </code></pre>