> Many times when I am writing some program in python, I notice that I
> could transform my list into set, then use the set methods like union,
> intersection, set equality etc. , and it will solve my problem easily.
> But then I realize that if I transform my list into set, it will
> remove duplicates of elements in the list and so I will lose
> information from my original list.
>
> For example, I was writing a program to detect whether two strings are
> anagrams of each other. I had to write it like this:
>
> def isAnagram(w1, w2):
> w2=list(w2)
> for c in w1:
> if c not in w2:
> return False
> else:
> w2.remove(c)
> return True
>
> But if there was a data structure in python which supported duplicate
> elements(lets call it dset), then I could just write:
>
> def inAnagram(w1,w2):
> return dset(w1)==dset(w2)
>
> Example of some dset methods:
> {1,2,3,3} intersection {4,1,2,3,3,3} == {1,2,3,3}
> {1,2,3,3} union {4,1,2,3,3,3} == {1,2,3,3,3,4}
> {4,1,2,3,3,3} difference {1,2,3,3} == {4,3}
>
> Do you think that it would be a good idea to add this kind of data
> structure to python? Or did I overlook some other easy way to solve
> this kind of problems?
I think collections.Counter object may be useful for your purpose.
http://docs.python.org/py3k/library/collections.html#collections.Counter
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