assign n seats proportionaly to votes using the https://en.wikipedia.org/wiki/Hagenbach-Bischoff_quota method

proportional.py

def proportional(nseats,votes):
    """assign n seats proportionaly to votes using the https://en.wikipedia.org/wiki/Hagenbach-Bischoff_quota method
    :param nseats: int number of seats to assign
    :param votes: iterable of int or float weighting each party
    :result: list of ints seats allocated to each party
    """
    quota=sum(votes)/(1.+nseats) #force float
    frac=[vote/quota for vote in votes]
    res=[int(f) for f in frac]
    n=nseats-sum(res) #number of seats remaining to allocate
    if n==0: return res #done
    if n<0: return [min(x,nseats) for x in res] #to handle case where votes=[0,0,..,1,0,...,0]
    #give the remaining seats to the n parties with the largest remainder
    remainders=[ai-bi for ai,bi in zip(frac,res)]
    limit=sorted(remainders,reverse=True)[n-1]
    for i,r in enumerate(remainders):
        if r>=limit:
            res[i]+=1
            n-=1 # attempt to handle perfect equality
            if n==0: return res #done
    raise #should never happen

See http://stackoverflow.com/questions/16226991/allocate-an-array-of-integers-proportionally-compensating-for-rounding-errors/20054616 (and vote it please)

added lien if n<0: return [min(x,nseats) for x in res] to handle case where votes=[0,0,..,1,0,...,0]

blog article on this topic (in french) http://www.drgoulu.com/2013/12/02/repartition-proportionnelle/