Summing multiple values of each key in a dict?

Question

I have a python dictionary, which looks like this.

{ \'item1\' : [1,2,3,4,5,6],
  \'item2\' : [2,3,1],
   .
   .
   .
  \'item n\' : [4,2,4,3,2]
}

Answer 1

This seems unnecessarily complicated. If you have your input as

inpt = { 'item1' : [1,2,3,4,5,6],
         'item2' : [2,3,1],
         .
         .
         .
         'item n' : [4,2,4,3,2]
       }

you can then use a dictionary comprehension instead:

out = {k: [sum(inpt[k])] for k in inpt.keys()}

Answer 2

items = {'item1' : [1,2,3,4,5,6],
  'item2' : [2,3,1],
  'item3' : [4,2,4,3,2]
}

for key, values in items.items():
    items[key] = sum(values)

Answer 3

You could create the dictionary with the sums on-the-fly:

Result = dict([(key, sum(values)) for key, values in yourDict.items()])
# or...
Result = {key: sum(values) for key, values in yourDict.items()}

Here, the values of the new dictionary will be numbers, but if you really need them to be lists, you could enclose the call to sum in square brackets: [sum(values)].