matching objects by a tuple field criterion

[Diez B. Roggisch]

Diez B. Roggisch schrieb:
> bullockbefriending bard schrieb:
>> i have a large collection of python objects, each of which contains an
>> integer 6-tuple as part of its data payload. what i need to be able to
>> do is select only those objects which meet a simple tuple element
>> wildcard matching criterion. e.g. given the following python objects:
>>
>>     object A includes tuple (1,2,3,4,5,6)
>>     object B includes tuple (1,4,4,4,11,1)
>>     object C includes tuple (1,3,9,1,1,1)
>>
>> all tuples are unique. for what it's worth, the values in each field
>> are independent of the other fields and range from 1 to 14. although
>> 'large', my collection is sparse cf. the 14^6 possible tuples.
>>
>> i want to search on *one only* tuple field/value. if my search
>> criterion is (*,*,*,4,*,*), then i want to find object A and object B.
>> if (1,*,*,*,*,*), i want to find objects A, B, and C, etc. i will only
>> ever specify an integer match for one tuple field.
>>
>> i can think of some naive approaches, but is there an elegant way to
>> do this?
> 
> Depends on what you find elegant. Are the criteria runtime-specified, 
> and is anything other than the * allowerd, e.g. [1,3,8]? IMHO the best 
> thing is to create a filter-function that you then use to... filter :)
> 
> Like this:
> 
> def create_filter_predicate(criteria):
>     """
>     criteria is an iterable containing either
>     an '*' or a list of comma-separated
>     integers
>     """
>     sub_preds = []
>     for i, sub_crit in enumerate(criteria):
>         if sub_crit == "*":
>            continue
>         matching_set = set(int(n) for n in sub_crit.split(","))
>         sub_preds.append((i, matching_set))
>     def predicate(o):
>         t = o.my_tuple
>         for i, ms in sub_preds:
>             if not t[i] in ms:
>                return False
>         return True
>     return predicate

Obviously the docs are faulty - the criteria looks like this:

['*', '1,2,3']

But I think you can get the gist of it - regardless on how the actual 
criteria are entered.

Diez