Question

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Python: simple list merging based on intersections

I have a multiple list:

 list=[[1,2,3],[3,5,6],[8,9,10],[11,12,13]]

Is there a smart and fast way to get all the sublists with at least one intersection. In my example I want that the code return

 result=[[1,2,3,5,6],[8,9,10],[11,12,13]]

Answer 1

This works, but maybe isn’t very elegant:

def merge_lists(l):
        s=map(set, l)
        i, n=0, len(s)
        while i < n-1:
                for j in xrange(i+1, n):
                        if s[i].intersection(s[j]):
                                s[i].update(s[j])
                                del s[j]
                                n-=1
                                break
                else:
                        i+=1
        return [sorted(i) for i in s]