Connecting the dots clear solution for Bigger Price by veky - python coding challenges

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Connecting the dots solution in Clear category for Bigger Price by veky

import operator, heapq, functools
bigger_price = functools.partial(heapq.nlargest, key=operator.itemgetter('price'))

April 25, 2018

Comments:

veky on April 27, 2018, 8:29 p.m.
@oduvan: Much improvement. I usually solve your missions with just one import from stdlib, now I had to use three. :-D

ilya.tleukenov on Dec. 5, 2018, 3:58 a.m.
<pre class='brush: python'>bigger_price = functools.partial(heapq.nlargest, key=operator.itemgetter('price')) </pre> Can't undestand syntactic use of functools.partial in your solution, when compared with documentation: <a href="https://docs.python.org/3/library/functools.html">https://docs.python.org/3/library/functools.html</a> <pre class='brush: python'>operator.itemgetter('price') </pre> it return a callable object that fetches item from its operand using the operand’s getitem() method, for list of dicts it's work like: for i in list: return i['price'] and fetch result in tuple <pre class='brush: python'>heapq.nlargest </pre> it's equivalent to: sorted(iterable, key=key, reverse=True)[:n], no questions but next like I think: functools.partial get a tuple from key=operator.itemgetter('price') and used func heapq.nlargest. But in documentation: <blockquote> functools.partial(func, args, *keywords) Return a new partial object which when called will behave like func called with the positional arguments args and keyword arguments keywords. If more arguments are supplied to the call, they are appended to args. If additional keyword arguments are supplied, they extend and override keywords: </blockquote> Can you explain solution for beginners, thanks

veky on Dec. 5, 2018, 6:23 a.m.
Let's try to explain. But I must say up front, I don't see what is your problem. You quote a bunch of documentation, and never say what is wrong with it. I'll try to walk you through, but you'll probably have further questions. Feel free to ask them. The solution is a "partial function". What does it mean? It's a function where you fix some arguments to known values, leaving others unspecified. The idea is very simple: "squaring" is just pow with exponent fixed at 2. "successor" is just + with right summand fixed at 1. Got it? Now, what I say here, `biggerprice` is just `heapq.nlargest` with `key` fixed at `operator.itemgetter('price')`. Do you got that? When I call `biggerprice` with some arguments `n` and `it`, I in fact call `heapq.nlargest` with arguments `n` and `it`, but with `key` equal to the specified item getter. And as you said, it gives me `n` largest elements from `it`, with respect to the specified key.

ilya.tleukenov on Dec. 5, 2018, 8:36 a.m.
<blockquote> I don’t see what is your problem. </blockquote> At first I don't understand why use key when basic syntactic of partial not included it: <pre class='brush: python'>functools.partial(func, *args, **keywords) </pre> But then I read your answer and documentation again and got it. key=operator.itemgetter(‘price’) - it's keywords for **func = heapq.nlargest And then n add to *args <blockquote> If more arguments are supplied to the call, they are appended to args </blockquote> Thanks for answer.

lsdda on Dec. 23, 2018, 12:50 a.m.
Always enlightening.

bsquare on Sept. 18, 2019, 1:56 p.m.
Very nice solution, your way to solve them is always ... special ^^

veky on Sept. 18, 2019, 2:03 p.m.
I just connected three dots. :-D

samarism on Sept. 15, 2020, 7:11 a.m.
use of heapq optimizes for time complexity. use of partial function is also elegant!

veky on Sept. 16, 2020, 4:27 p.m.
It also optimizes for number of defs/lambdas. :-]

Jonethan on Sept. 25, 2020, 9:33 a.m.
wow.. it's a short using

veky on Sept. 25, 2020, 11:13 a.m.
I didn't quite understand. Using what?

2010min0ru on Oct. 15, 2020, 10:02 a.m.
Very interesting and smart solution. Forced me into looking into heapq :)

veky on Oct. 15, 2020, 10:30 a.m.
Then it has fulfilled its purpose. :-)

leggewie on May 24, 2021, 1:28 p.m.
bookmarked, I will need to come back to this to check out what's going on here I really like your unconventional solutions, keep it up

veky on May 24, 2021, 3:13 p.m.
I don't know about conventions, but this is straightforward (if you keep Python stdlib reference under your pillow as instructed;)). It uses the functions in exactly the manner they are supposed to be used. ;-)

leggewie on May 24, 2021, 4:31 p.m.
Well, conventional or not, I guess you can judge how "mainstream" this solution is by the number of other people coming up with these kinds of solutions. Maybe "unique" or "clever" would be a better word than "unconventional". In other words, a solution that surprises me (and possibly others). I'm the kind of guy who enjoys seeing such "unconventional" solutions. Much more enjoyable than reconfirming yourself by seeing the fiftieth guy who did it the same way as oneself. I hope this clears up the confusion ;-)

veky on May 24, 2021, 4:41 p.m.
Oh, I'm sorry about the confusion about the confusion. I wasn't confused. :-) Yes, I know what are you talking about, and that is one of my main reasons to write these solutions (and of course, it is the main reason for the number of points I have here:). I just wanted to point out that using nlargest instead of sorting and slicing last n (being algorithmically faster) and setting itemgetter as a key (being much more DRY and avoiding needless lambdas) are precisely the reasons why those functions were added to stdlib. I didn't have to force a lesson here, the mission was natural for that. (partial is just an artefact of CiO's testing system, since it expects a function. In real life, if I had to do that, I'd just write <pre class='brush: python'>top_prices = nlargest(prices, 7, key=itemgetter('price')) </pre> -- that is, I wouldn't use partial since it's unnecessary if you just want to calculate the result directly. But I would still use nlargest and key=itemgetter, since they are one obvious way to do it.;)

titaevskaya on Sept. 7, 2021, 4:20 p.m.
great usage of partial!!!

Klimchick on March 6, 2022, 7:19 p.m.
When I'm making a code in 50 strings you are making it in a one...)))))

veky on March 7, 2022, 6:50 a.m.
Just three dots. ;-)

Look up in the Dict()

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