On Thursday, September 6, 2018 at 12:12:20 PM UTC-7, David Raymond wrote: > The actual "enumerate" object is really just holding a current index and a > reference to the original list. So if you alter the original list while > you're iterating through it you'll see the changes. If you want a full copy > then you can just wrap it with list() > > Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:59:51) [MSC v.1914 64 bit > (AMD64)] on win32 > Type "help", "copyright", "credits" or "license" for more information. > >>> numList = [2, 7, 22, 30, 1, 8] > >>> aList = enumerate(numList) > >>> aList.__next__() > (0, 2) > >>> numList[1] = 5 > >>> aList.__next__() > (1, 5) > >>> aList2 = list(enumerate(numList)) > >>> aList2 > [(0, 2), (1, 5), (2, 22), (3, 30), (4, 1), (5, 8)] > >>> numList[3] = -12 > >>> aList2 > [(0, 2), (1, 5), (2, 22), (3, 30), (4, 1), (5, 8)] > >>> aList.__next__() > (2, 22) > >>> aList.__next__() > (3, -12) > >>> aList.__next__() > (4, 1) > >>> aList.__next__() > (5, 8) > >>> aList.__next__() > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > StopIteration > >>> > > > -----Original Message----- > From: Python-list > [mailto:python-list-bounces+david.raymond=tomtom....@python.org] On Behalf Of > Viet Nguyen via Python-list > Sent: Thursday, September 06, 2018 2:50 PM > To: python-list@python.org > Subject: Re: Why emumerated list is empty on 2nd round of print? > > On Thursday, September 6, 2018 at 10:34:19 AM UTC-7, Chris Angelico wrote: > > On Fri, Sep 7, 2018 at 3:26 AM, Viet Nguyen via Python-list > > <python-list@python.org> wrote: > > >>>> numList > > > [2, 7, 22, 30, 1, 8] > > > > > >>>> aList = enumerate(numList) > > > > > >>>> for i,j in aList:print(i,j) > > > > > > 0 2 > > > 1 7 > > > 2 22 > > > 3 30 > > > 4 1 > > > 5 8 > > > > > >>>> for i,j in aList:print(i,j) > > > > > >>>> > > > > Because it's not an enumerated list, it's an enumerated iterator. > > Generally, you'll just use that directly in the loop: > > > > for i, value in enumerate(numbers): > > > > There's generally no need to hang onto it from one loop to another. > > > > ChrisA > > Thanks ChrisA. If I do this "aList = enumerate(numList)", isn't it stored > permanently in aList now? I see your point to use it directly, but just in > case I do need to hang onto it from one loop to another, then how is that > done? Anyway I think I'm ok and I got what I need for now. > -- > https://mail.python.org/mailman/listinfo/python-list
Very clear and good examples! Thank you. -- https://mail.python.org/mailman/listinfo/python-list
