Mostly so that there is no performance lost when someone passes range(...) instead of np.arange(...). At least I had never realized that one is much faster than the other and always just passed range() as a convenience.
Antony 2016-02-17 10:50 GMT-08:00 Chris Barker <chris.bar...@noaa.gov>: > On Sun, Feb 14, 2016 at 11:41 PM, Antony Lee <antony....@berkeley.edu> > wrote: > >> So how can np.array(range(...)) even work? >> > > range() (in py3) is not a generator, nor is is a iterator. it is a range > object, which is lazily evaluated, and satisfies both the iterator protocol > and the sequence protocol (at least most of it: > > In [*1*]: r = range(10) > > > In [*2*]: r[3] > > Out[*2*]: 3 > > > In [*3*]: len(r) > > Out[*3*]: 10 > > > In [*4*]: type(r) > > Out[*4*]: range > > In [*9*]: isinstance(r, collections.abc.Sequence) > > Out[*9*]: True > > In [*10*]: l = list() > > In [*11*]: isinstance(l, collections.abc.Sequence) > > Out[*11*]: True > > In [*12*]: isinstance(r, collections.abc.Iterable) > > Out[*12*]: True > I'm still totally confused as to why we'd need to special-case range when > we have arange(). > > -CHB > > > > -- > > Christopher Barker, Ph.D. > Oceanographer > > Emergency Response Division > NOAA/NOS/OR&R (206) 526-6959 voice > 7600 Sand Point Way NE (206) 526-6329 fax > Seattle, WA 98115 (206) 526-6317 main reception > > chris.bar...@noaa.gov > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > https://mail.scipy.org/mailman/listinfo/numpy-discussion > >
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