Compare tuples of different lenght

Jurgens de Bruin debruinjj at gmail.com
Sat Aug 20 12:47:29 CEST 2011


On Aug 20, 12:17 pm, Steven D'Aprano <steve
+comp.lang.pyt... at pearwood.info> wrote:
> Jurgens de Bruin wrote:
> > Hi,
>
> > I have a list of tuples:
>
> > [(2,),(12,13),(2,3,4),(8,),(5,6),(7,8,9),]
>
> > I would like to compare all the tuples to each other and if one
> > element if found two tuples the smallest tuples is removed from the
> > list.
>
> It's not clear what you mean by "smallest" tuple. Is (8,) smaller than
> (7,8,9)?
>
> I'm going to guess you care only about the length of the tuple, and not the
> items themselves.
>
> Let's start with a couple of helper functions.
>
> def compare(t1, t2):
>     'Return -1 if t1 is "smaller" than t2, 0 if equal, and +1 if "bigger".'
>     if len(t1) < len(t2): return -1
>     elif len(t1) > len(t2): return 1
>     else: return 0
>
> def match_any_item(t1, t2):
>     try:
>         s1 = set(t1)
>         s2 = set(t2)
>         return bool(s1 & s2)
>     except TypeError:
>         # Can't convert to sets because at least one item is mutable.
>         # Let's do this the slow(?) way.
>         matched = [x for x in t1 if x in t2]
>         return bool(matched)
>
> list_of_tuples = [(2,),(12,13),(2,3,4),(8,),(5,6),(7,8,9),]
> flags = [True]*len(list_of_tuples)
> for i,t1 in enumerate(list_of_tuples):
>     for j in range(i+1, len(list_of_tuples)):
>         t2 = list_of_tuples[j]
>         if match_any_item(t1, t2):
>             n = compare(t1, t2)
>             if n == -1:
>                 # Flag t1 to be removed.
>                 flags[i] = False
>             elif n == 1:
>                 # Flag t2 to be removed.
>                 flags[j] = False
>
> saved_tuples = []
> for t,flag in zip(list_of_tuples, flags):
>     if flag: saved_tuples.append(t)
>
> This gives:
>
> >>> saved_tuples
>
> [(12, 13), (2, 3, 4), (5, 6), (7, 8, 9)]
>
> which matches what you wanted:
>
> > [(12,13),(2,3,4),(5,6),(7,8,9),]
>
> --
> Steven

Thanks Steven. This works great!!!

Appreciated very much!!!



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