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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