[Tutor] Functional question
Kent Johnson
kent37 at tds.net
Fri Aug 5 22:32:08 CEST 2005
Bernard Lebel wrote:
> Hello,
>
> This question is not strictly bound to Python, but rather some
> functional programming problem, I hope someone can help me or suggest
> ressources.
>
> 1 --
> I have a list of lists. Each of these lists has 3 elements: a string,
> and two integers. Thoughout the lists, there are only two different
> integers for the first one, and two different for the second one.
>
> aLists = [
> [ 'Pass1', 10, 200 ],
> [ 'Pass2', 10, 200 ],
> [ 'Pass3', 25, 100 ],
> [ 'Pass4', 10, 100 ],
> [ 'Pass5', 25, 200 ] ]
>
>
>
> 2 --
> Then I want to regroup the strings into two dictionaries. The first
> dictionaries is for the strings that have the same first integer, and
> the second dictionay is for the strings that have the same second
> integer.
>
> dMap1 = {}
> dMap2 = {}
>
> # Iterate lists
> for aList in aLists:
>
> sPass = aList[0]
> iValue1 = aList[1]
> iValue2 = aPList[2]
>
> # Map pass name to integers
> dMap1.setdefault( iValue1, [] ).append( sPass )
> dMap2.setdefault( iValue2, [] ).append( sPass )
If I understand you correctly, you want to group the strings that have both integers the same. Just use the tuple (iValue1, iValue2) as the key in a third dictionary:
dmap3.setdefault( (iValue1, iValue2), [] ).append( sPass )
Kent
> So far so good, it's working, I end up with this structure:
>
> dMap1 = {
> 10 : [ 'Pass1', 'Pass2', 'Pass4' ],
> 25 : [ 'Pass3', 'Pass5' ] }
>
> dMap2 = {
> 100 : [ 'Pass3', 'Pass4' ],
> 200 : [ 'Pass1', 'Pass2', 'Pass5' ] }
>
>
> 3 --
> This is where I'm completely stump.
> I want to consolidate the strings into another dictionary the strings
> that share the same integers, resulting in such a structure:
>
> dGroups = {
> 'group0' : [ 'Pass1', 'Pass2' ], # 10, 200
> 'group1' : [ 'Pass4' ], # 10, 100
> 'group2' : [ 'Pass3' ], # 25, 100
> 'group3' : [ 'Pass5' ], # 25, 200 }
>
> However, I have absolutely no idea how to achieve that third dictionary!
>
>
>
> Thanks
> Bernard
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