Thanks first, I could understand the second approach easily. The first approach is a bit puzzling. Why are seen=set() and seen.add(x) still necessary there if we can use unique.append(x) alone? Thanks for your enlightenment.
On Sun, Sep 9, 2012 at 1:59 PM, Donald Stufft <donald.stu...@gmail.com>wrote: > seen = set() > uniqued = [] > for x in original: > if not x in seen: > seen.add(x) > uniqued.append(x) > > or > > uniqued = [] > for x in oriignal: > if not x in uniqued: > uniqued.append(x) > > The difference between is option #1 is more efficient speed wise, but uses > more memory (extraneous set hanging around), whereas the second is slower > (``in`` is slower in lists than in sets) but uses less memory. > > On Sunday, September 9, 2012 at 1:56 AM, John H. Li wrote: > > Many thanks. If I want keep the order, how can I deal with it? > or we can list(set([1, 1, 2, 3, 4])) = [1,2,3,4] > > > On Sun, Sep 9, 2012 at 1:47 PM, Donald Stufft <donald.stu...@gmail.com>wrote: > > If you don't need to retain order you can just use a set, > > set([1, 1, 2, 3, 4]) = set([1, 2, 3, 4]) > > But set's don't retain order. > > On Sunday, September 9, 2012 at 1:43 AM, Token Type wrote: > > Is there a unique method in python to unique a list? thanks > -- > http://mail.python.org/mailman/listinfo/python-list > > > > >
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