Yes, I mean zip compression :) Also, everyone's been posting decode functions, but encode is a bit harder :).
I think it should be equally easy to go one direction as the other. Hopefully this email chain builds up enough info to update the docs for posterity / future me. On Sat, Jun 10, 2017 at 8:27 PM, Joshua Morton <joshua.morto...@gmail.com> wrote: > David: You're absolutely right, s/2/3 in my prior post! > > Neal: As for why zip (at first I thought you meant the zip function, not > the zip compression scheme) is included and rle is not, zip is (or was), I > believe, used as part of python's packaging infrastructure, hopefully > someone else can correct me if that's untrue. > > --Josh > > On Sat, Jun 10, 2017 at 8:20 PM David Mertz <me...@gnosis.cx> wrote: > >> God no! Not in the Python 2 docs! ... if the recipe belongs somewhere >> it's in the Python 3 docs. Although, I suppose it could go under 2 also, >> since it's not actually a behavior change in the feature-frozen >> interpreter. But as a Python instructor (and someone who remembers the >> cool new features of Python 1.5 over 1.4 pretty well), my attitude about >> Python 2 is "kill it with fire!" >> >> Your spelling of the one-liner is prettier, shorter, and more intuitive >> than mine, and the same speed. >> >> On Sat, Jun 10, 2017 at 8:12 PM, Joshua Morton <joshua.morto...@gmail.com >> > wrote: >> >>> Another is >>> >>> [(k, len(list(g))) for k, g in groupby(l)] >>> >>> >>> It might be worth adding it to the list of recipies either at >>> https://docs.python.org/2/library/itertools.html#itertools.groupby or >>> at https://docs.python.org/2/library/itertools.html#recipes, though. >>> >>> On Sat, Jun 10, 2017 at 8:07 PM David Mertz <me...@gnosis.cx> wrote: >>> >>>> Here's a one-line version: >>>> >>>> from itertools import groupby >>>> rle_encode = lambda it: ( >>>> (l[0],len(l)) for g in groupby(it) for l in [list(g[1])]) >>>> >>>> Since "not every one line function needs to be in the standard library" >>>> is a guiding principle of Python, and even moreso of `itertools`, probably >>>> this is a recipe in the documentation at most. Or maybe it would have a >>>> home in `more_itertools`. >>>> >>>> >>>> On Sat, Jun 10, 2017 at 7:20 PM, Neal Fultz <nfu...@gmail.com> wrote: >>>> >>>>> Hello python-ideas, >>>>> >>>>> I am very new to this, but on a different forum and after a couple >>>>> conversations, I really wished Python came with run-length encoding >>>>> built-in; after all, it ships with zip, which is much more complicated :) >>>>> >>>>> The general idea is to be able to go back and forth between two >>>>> representations of a sequence: >>>>> >>>>> [1,1,1,1,2,3,4,4,3,3,3] >>>>> >>>>> and >>>>> >>>>> [(1, 4), (2, 1), (3, 1), (4, 2), (3, 3)] >>>>> >>>>> where the first element is the data element, and the second is how >>>>> many times it is repeated. >>>>> >>>>> I wrote an encoder/decoder in about 20 lines ( >>>>> https://github.com/nfultz/rle.py/blob/master/rle.py ) and would like >>>>> to offer it for the next version; I think it might fit in nicely in the >>>>> itertools module, for example. I am curious about your thoughts. >>>>> >>>>> Best, >>>>> >>>>> -Neal >>>>> >>>>> _______________________________________________ >>>>> Python-ideas mailing list >>>>> Python-ideas@python.org >>>>> https://mail.python.org/mailman/listinfo/python-ideas >>>>> Code of Conduct: http://python.org/psf/codeofconduct/ >>>>> >>>>> >>>> >>>> >>>> -- >>>> Keeping medicines from the bloodstreams of the sick; food >>>> from the bellies of the hungry; books from the hands of the >>>> uneducated; technology from the underdeveloped; and putting >>>> advocates of freedom in prisons. Intellectual property is >>>> to the 21st century what the slave trade was to the 16th. >>>> _______________________________________________ >>>> Python-ideas mailing list >>>> Python-ideas@python.org >>>> https://mail.python.org/mailman/listinfo/python-ideas >>>> Code of Conduct: http://python.org/psf/codeofconduct/ >>>> >>> >> >> >> -- >> Keeping medicines from the bloodstreams of the sick; food >> from the bellies of the hungry; books from the hands of the >> uneducated; technology from the underdeveloped; and putting >> advocates of freedom in prisons. Intellectual property is >> to the 21st century what the slave trade was to the 16th. >> >
_______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
