Perhaps a NamedList would be helpful here? One could write one fairly easily.
-CHB On Fri, Jun 26, 2020 at 6:13 PM Steven D'Aprano <st...@pearwood.info> wrote: > On Fri, Jun 26, 2020 at 10:45:07AM -0700, Brett Cannon wrote: > > > Why can't you do `tuple(dict.items())` to get your indexable pairs? > > I don't think that an immutable copy is going to help Hans with his > use-case, since he already mentions that tuples don't solve his problem. > > Swapping to a list gives you a mutable sequence that makes inserting > columns easy, but now lookups by column name are O(N) instead of O(1). > > Hans, I think that a dict is probably not the best solution here, but > you can use a dict in an augmented data structure. I would consider > keeping your columns in a list, indexed by position, and keeping a table > of columns to index in a dict. Whenever you insert or remove a column, > you can update the table. > > If this sounds like a lot of work, yes, it probably is, and making dicts > perform that work for *every single dict* would slow down the language a > lot. Dicts are critical for speed and performance because they are used > so extensively. Globals, builtins, almost every module, class and > instance use dicts internally, so they need to be as fast as possible. > > If your experience with Perl tells you differently, please explain to us > how Perl hashes work in order that they support both fast hash indexing > and positional indexing at the same time. > > > -- > Steven > _______________________________________________ > 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/POHINM764UHZKVXK3GWOYIJPF525IDCS/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Christopher Barker, PhD Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython
_______________________________________________ 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/YE7NC54KA4J7ESZRM4ZFE472QFGNYVEY/ Code of Conduct: http://python.org/psf/codeofconduct/
