title: Summing multiple values of each key in a dict?
body: <p>I have a python dictionary, which  looks like this.</p>
  
  <pre><code>{ 'item1' : [1,2,3,4,5,6],
    'item2' : [2,3,1],
     .
     .
     .
    'item n' : [4,2,4,3,2]
  }
  </code></pre>
  
  <p>Now my requirement is that i want to add the numeric values of this dict &amp; to show it as :-</p>
  
  <pre><code>{    'item1' : [21],
       'item2' : [6],
        .
        .
        .
       'item n' : [15]
  }
  </code></pre>
  
  <p>I just want the multiple values of each key to be summed up &amp; displayed. FYI, I am using an append function. Below is my code.</p>
  
  <pre><code>for row in range(2,sheet2.max_row):
      for column in "D": 
          cell_name = "{}{}".format(column, row)
      for column2 in "P":
          cell_name2 = "{}{}".format(column2,row)
          arrdata2dict.setdefault(sheet2[cell_name].value,[])
          arrdata2dict[sheet2[cell_name].value].append(sheet2[cell_name2].value)
  </code></pre>