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. >
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