Duplicate keys in dict?

[vsoler]

On 7 mar, 17:53, Steven D'Aprano <st... at REMOVE-THIS-
cybersource.com.au> wrote:
> On Sun, 07 Mar 2010 08:23:13 -0800, vsoler wrote:
> > Hello,
>
> > My code snippet reads data from excel ranges. First row and first column
> > are column headers and row headers respectively. After reding the range
> > I build a dict.
>
> > ................'A'..............'B'
> > 'ab'............3................5
> > 'cd'............7................2
> > 'cd'............9................1
> > 'ac'............7................2
>
> > d={('ab','A'): 3, ('ab','B'): 5, ('cd','A'): 7, ...
>
> > However, as you can see there are two rows that start with 'cd', and
> > dicts, AFAIK do not accept duplicates.
> > One of the difficulties I find here is that I want to be able to easily
> > sum all the values for each row key:  'ab', 'cd' and 'ac'. However,
> > using lists inside dicts makes it a difficult issue for me.
>
> Given the sample above, what answer do you expect for summing the 'cd'
> row? There are four reasonable answers:
>
> 7 + 2 = 9
> 9 + 1 = 10
> 7 + 2 + 9 + 1 = 19
> Error
>
> You need to decide what you want to do before asking how to do it.
>
> --
> Steven

Steven,

What I need is that sum(('cd','A')) gives me 16, sum(('cd','B')) gives
me 3.

I apologize for not having made it clear.