Le sam. 2 oct. 2021 à 15:54, <python-ideas-requ...@python.org> a écrit : > Date: Sat, 2 Oct 2021 12:45:33 +0200 > From: Laurent Lyaudet <laurent.lyau...@gmail.com> > Subject: [Python-ideas] Feature request enumerate_with_rest or > enumerate with skip or filter callback > To: python-ideas@python.org > Message-ID: > <CAB1LBmsXQJbeLuyK6tG8aP=kb36DAR==vcajo-zhuhjgnfv...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Hello, > > This is a very simple feature request that does not break anything but > I don't know if you may find it interesting. > It would be nice to have a function or method of list objects that does this : > - First idea : > def enumerate_with_rest(my_list): > for i, item in enumerate(my_list): > yield i, item, my_list[:i] + my_list[i + 1:] > > It could be called easily with: > > for i, item, rest in enumerate_with_rest(my_list): > # do something > > or > for i, item, rest in my_list.enumerate_with_rest(): > # do something > > I am not the only one who had the same need : > https://stackoverflow.com/questions/56966429/getting-pairs-of-one-item-and-the-rest-over-a-python-list > > It would be nice to have an optimized C function for this. > However, it may be less interesting than this : > - Second idea > enumerate_with_rest above has quadratic complexity. > It is probably true that most processes that use it will also have > quadratic complexity. > However, it would be better to return an iterator instead of a list > for the rest, > it would use less space. > For this a param skip to enumerate would do the job > def enumerate_with_rest(my_list): > for i, item in enumerate(my_list): > yield i, item, enumerate(my_list, skip=i) > There could be variants of this idea like : > - enumerate(my_list, skip=i) > - enumerate(my_list, skip=[i]) > - enumerate(my_list, filter_callback=(lambda x: x != i)) > > Please let me know what you think of it :) > > Thanks for your time, best regards, > Laurent Lyaudet Hello, Regarding the last suggestion. - enumerate(my_list, filter_callback=(lambda x: x != i)) The idea is to filter a list by indices : a quick search for that just yields : https://stackoverflow.com/questions/11847491/python-filtering-lists-by-indices which is not really helpful Since filter() returns an iterator instead of a list, it could do what is needed... if the callback had access to the index like the Javascript array filter function. > def enumerate_with_rest(my_list): > for i, item in enumerate(my_list): > yield i, item, my_list[:i] + my_list[i + 1:] could also be : def enumerate_with_rest(my_list): for i, item in enumerate(my_list): yield i, item, filter_by_index(my_list, lambda x: x != i)
I think my feature request for enumerate_with_rest is maybe too specific. However, I think there should definitely be in itertools something to filter indices like JS permits. I have not found a function to do this there: https://docs.python.org/3/library/functions.html https://docs.python.org/3/library/itertools.html What would be your prefered way of doing this ? enumerate(my_list, filter_callback=(lambda x: x != i)) filter_by_index(my_list, lambda x: x != i) # à la JS filter(my_list, lambda _, x: x != i) Currently, the following solution is available : filter(enumerate(my_list), lambda x: x[0] != i) But it is slightly ugly and unefficient to have two function calls for such a simple task I think. I would appreciate any feedback; even if none of my ideas are accepted, I may learn something :) Best regards, Laurent Lyaudet _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/U224WQJP5P3D6YV523EGT4F74JFDJ5W5/ Code of Conduct: http://python.org/psf/codeofconduct/
