Cookbook: Associating multiple values with each key in a dictionary

[Egbert Bouwman]

On Tue, Jul 30, 2002 at 01:14:14PM -0400, Michael Gilfix wrote:
> 
>   I'm not really sure why you prefer the list method. Is there something
> that you can't accomplish with the nested dictionaries?

When I need
  { 'boys': ['mike', 'egbert'], 'girls': ['laura','lisa'] }
it hurts me when I have to build:  
  { 'boys': {'mike' : 1, 'egbert' : 1}, 'girls': {'laura' : 1,'lisa' : 1} }
  
That adds an extra layer of complexity when i construct it,
I have to remember or document that the values can be thrown away,
and I have now sets of keys, while I need sets of values.

I try to be a good pythonista, so I and simplicity come first, 
and efficiency and implementation come second.

Of course that all changes when I really need the values, ie when
they don't have some dummy value anymore. But in that case 
we simply have a nested dictionary, which is not our subject now.

As an afterthought: is it necessary that lists are slower than
dictionaries ?  Cannot they be subjected to some hash machine as well ?
At least in some cases, ie when you search in lists ?

egbert
-- 
Egbert Bouwman - Keizersgracht 197 II - 1016 DS  Amsterdam - 020 6257991
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