On Sun, Dec 2, 2018 at 12:49 PM Chris Angelico <ros...@gmail.com> wrote:
> On Sun, Dec 2, 2018 at 10:36 PM Morten W. Petersen <morp...@gmail.com> > wrote: > > While we're on the subject, I did a test in my Python interpreter: > > > > Python 3.6.7 (default, Oct 22 2018, 11:32:17) > > [GCC 8.2.0] on linux > > Type "help", "copyright", "credits" or "license" for more information. > > >>> range(0,3,100) > > range(0, 3, 100) > > >>> len(range(0,3,100)) > > 1 > > >>> range(0,100) > > range(0, 100) > > >>> len(range(0,100)) > > 100 > > >>> > > > > Where a range with a step, gives the length 1, while a plain range gives > > the right length. > > > > I think that's confusing and inconsistent, and it would be nice to have > some > > "value to be calculated" for the length integer as well. > > > > Possibly you're misinterpreting the arguments here. > > >>> list(range(0, 3, 100)) > [0] > > class range(object) > | range(stop) -> range object > | range(start, stop[, step]) -> range object > | > > The *third* argument is the step, so if you were expecting "every > third number up to 100", you'd be looking for this: > > >>> len(range(0, 100, 3)) > 34 > >>> len(list(range(0, 100, 3))) > 34 > > To my knowledge, len(x) == len(list(x)) for any core data type that > has a length. > Ah yes, of course. I haven't had my coffee yet. :) >>> len(range(0,100,3)) 34 >>> range(0,100,3).__len__ <method-wrapper '__len__' of range object at 0x7f144d5e3210> >>> range(0,100,3).__len__() 34 >>> But again, I guess an integer-to-be-calculated would be suitable for iterators where it is very expensive to do a list or other similar calculation. These operations take quite a bit of time: >>> x=list(range(0,100000000,3)) >>> y=len(list(range(0,100000000,3))) >>> -Morten -- Videos at https://www.youtube.com/user/TheBlogologue Twittering at http://twitter.com/blogologue Blogging at http://blogologue.com Playing music at https://soundcloud.com/morten-w-petersen Also playing music and podcasting here: http://www.mixcloud.com/morten-w-petersen/ On Google+ here https://plus.google.com/107781930037068750156 On Instagram at https://instagram.com/morphexx/ -- https://mail.python.org/mailman/listinfo/python-list
