map can take more than 2 arguments clear solution for Ascending List by veky - python coding challenges

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map can take more than 2 arguments solution in Clear category for Ascending List by veky

import typing, itertools, operator

def is_ascending(items: typing.Iterable[int]) -> bool:
    items, shifted = itertools.tee(items)
    next(shifted, None)
    return all(map(operator.lt, items, shifted))

Oct. 14, 2018

Comments:

tarjeii on Nov. 24, 2018, 6:46 p.m.
Thanks for using this untraditional solution, but it would be nice with a brief description, I had to use the docs :)

veky on Nov. 25, 2018, 5:42 a.m.
<ol> <li>Why is using the docs so horrible? :-] For me it is the best way to learn.</li> <li>What kind of a description would help you? Despite how it looks from your perspective, it's not obvious. From my perspective, this was just a simple modification of the `pairwise` recipe available from <a href="https://docs.python.org/3/library/itertools.html">https://docs.python.org/3/library/itertools.html</a>#itertools-recipes.</li> </ol>

tarjeii on Nov. 25, 2018, 9:54 a.m.
<ol> <li>Difficult to argue against that. </li> <li>I guess it is not possible to satisfy everyone's needs since everyone has different starting points. In my case I was puzzled by the use of Tee.</li> </ol> Conclusion: read the docs

veky on Nov. 26, 2018, 4:50 a.m.
Yes, 2. is very important and the reason I like CiO so much. We have interactive discussions about the code, which is so much better than a fixed "comment block". As you can see from the title, I guessed most people would be interested to learn about map, but of course, there are other useful bits of knowledge in that code. :-)

s_m on Jan. 2, 2019, 11:44 a.m.
Hi, Veky! Happy New Year! Why should we specify <pre class='brush: python'>typing.Iterable[int] </pre> and why do we need to specify <pre class='brush: python'>[int] </pre> ? It is supposed to work without it. I have read python docs and I don't really understand what typing module is for in python. And why did you use 'itertools.tee' instead of 'iter'? Best regards.

veky on Jan. 2, 2019, 6:05 p.m.
<blockquote> I don’t really understand what typing module is for in python. </blockquote> It's not surprising, because it's not (really) for Python. :-9 It is meant for "structured documentation", usually for complicated projects which actually can benefit from them. You know, those when you start writing docstrings such as <pre class='brush: python'>@param x: float "first coordinate" </pre> C-: And there are tools that use them for static type checking, the most famous being mypy. Yes, using them on CiO is probably useless, but as I often say, the point of CiO is to learn about Python, not to solve tasks. And learning about type hints might be useful. <hr /> Concretely, typing.Iterable is a static type of iterables, the things that can be iterated over (usually via the for loop). It is in fact a generic type (not a concrete type), but when used as a concrete type, it stands for Iterable[Any]. (Iterable[T], where T is a static type, means an iterable of things of type T. So Iterable[int] means an iterable of ints.) <hr /> itertools.tee is really not the same as iter. People usually forget that iterators are themselves also iterables. And if i is an iterator, then iter(i) is i (literally). What tee does is it artificially duplicates any iterable (including iterators) so they can be "independently" iterated over. See also the comments above. Any more questions? :-)

s_m on Jan. 3, 2019, 5:15 p.m.
great explanation! Thank you so much! Why do you prefer Python? Are there any other algorithmic languages what you prefer? :)

veky on Jan. 3, 2019, 8:21 p.m.
Some details are <a href="https://py.checkio.org/mission/most-wanted-letter/publications/veky/python-3/key/share/558122d102fe7ac5bc9c2a6ceaaa84bb/#comment-33973">here</a>. For too long, I have erroneously believed that explaining algorithms to people and to computers are always at odds with one another, and can never really be reconciled. Python has finally showed me that it's possible to have a language that fulfills both roles quite harmoniously.

s_m on Jan. 4, 2019, 6:05 p.m.
Thx! Best regards!

leggewie on May 25, 2021, 1:57 p.m.
beautiful I learned quite a few new things from those very few lines. Let's see if I will remember them next time they'd come in handy ;-)

dan_rue on Nov. 26, 2022, 9:50 p.m.
Nice solution. I didn't knew you can use operators like that. I would have probably used a comprehension, but this is much better. I guess tee() is used, so u can 'next' the shifted iterator, right?

veky on Nov. 28, 2022, 12:15 p.m.
Look at the recipe for <a href="https://docs.python.org/3/library/itertools.html#itertools.pairwise">pairwise</a>.

H0r4c3 on April 29, 2023, 8:42 a.m.
Good advice! itertools.pairwise(iterable) - Return successive overlapping pairs taken from the input iterable. Roughly equivalent to: def pairwise(iterable): # pairwise('ABCDEFG') --> AB BC CD DE EF FG a, b = tee(iterable) next(b, None) return zip(a, b)

veky on April 29, 2023, 1:08 p.m.
You could have at least formatted that response as Python code. :-P

H0r4c3 on April 29, 2023, 9:18 p.m.
Sorry, my bad! How about this format? :-P <pre class='brush: python'>def pairwise(iterable): # pairwise('ABCDEFG') --> AB BC CD DE EF FG a, b = tee(iterable) next(b, None) return zip(a, b) </pre>

H0r4c3 on April 30, 2023, 8:09 a.m.
Another lesson learned here: how to comment correctly. I had no idea about the code format. Glad to be here! :) Thanks!

TheRing on Feb. 28, 2023, 9:29 p.m.
An interesting approach to compare adjacent elements in an iterable without using indices.

veky on March 2, 2023, 3:13 a.m.
Absolutely. It is the same recipe as used in itertools.pairwise. <a href="https://docs.python.org/3.8/library/itertools.html">https://docs.python.org/3.8/library/itertools.html</a>#itertools-recipes

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