When using sequence types polymorphically, range, list, and tuple are both iterable and subscriptable.  Unfortunately, itertools.count, cycle, and repeat objects are not subscriptable, although this is not a hard change.

Please consider making these objects subscriptable for polymorphic usage.

Range, list, and tuple are iterables, but itertools.count, cycle, and repeat objects are iterators. Subscripting is not a part of iterator protocol.

Apologies if this is a bad question, but why do count, cycle, and repeat return iterators rather than iterables?

The point of itertools is to implement building blocks for iterators, which are memory-efficient and can sometimes be infinite, contrary to sequences.

> Apologies if this is a bad question, but why do count, cycle, and repeat return iterators rather than iterables?

Actually they are iterables too.

My suggestion is then to update collection.abc to have an InfiniteSequence, which inherits from Iterable, and adds abstract methods __getitem__ and mixin methods __iter__.

Then, itertools count, cycle, and repeat could implement collection.abc.InfiniteSequence, and collections.abc.Iterator (for backwards-compatibility).

What kind of problem you want to solve? I'm sure there is a simple enough solution without changing itertools objects.

My code looks like this:

presignal_abd = [[], [0.1, 0.6], []]
tarsignal_abd = [[], [0.4, 0.9], []]
diagsignal_abd = [[], [0.1, 0.6, 0.7, 0.8], []]
# etc.

for (filename,
     observations,
     presignals,
     tarsignals,
     diagsignals,
     diagram_type) in zip(['events-deduction', 'events-abduction', 'events-accomodation', 'events-learning', 'events-learning-2'],
                          [observations_ded, observations_abd, observations_tra, observations_tra1, observations_tra],
                          [repeat_([]), presignal_abd, presignal_tra, repeat_([]), presignal_tra],
                          [repeat_([]), tarsignal_abd, tarsignal_tra, repeat_([]), tarsignal_tra],
                          [repeat_([]), diagsignal_abd, diagsignal_tra, repeat_([]), diagsignal_tra],
                          [0, 1, 2, 3, 3]):
    second_set_of_events = presignals[1]


I am using repeat_ objects (itertools.repeat objects) to fill as dummies.

Why not use `dummy = [[]] * 3` as dummy?

Thanks, that works.

One of the things I like about Python is that you can write what you mean.  I figured that since I meant "repeat [] as many times as necessary", that I should write it that way.  So, from an intuitive standpoint, I still feel that these itertools types intuitively implement InfiniteSequence.  Although I recognize that some people might see them only in the narrower sense of Iterators.