Lambada creative solution for Sort Array by Element Frequency by veky - python coding challenges

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Lambada solution in Creative category for Sort Array by Element Frequency by veky

frequency_sort = lambda a: sorted(a, key=lambda x: (-a.count(x), a.index(x)))

Dec. 6, 2018

Comments:

roncitrus on Feb. 22, 2019, 11:57 a.m.
awesome

bsquare on Sept. 18, 2019, 9:21 a.m.
Haha, this one is very nice, till need 2 readings ^^

gtmizyuk on April 2, 2020, 8:57 p.m.
good

natter1 on April 4, 2021, 12:37 p.m.
Why can we assume here that the given iterable (thats what was stated as input) has an index()-method? What e.g. about a set (of course, the sort is not useful in that case, but anyway) or something coming out of yield ...

veky on April 5, 2021, 4:26 a.m.
We can't. I'm quite sure that when I solved the task, the text said "list" or something like that (nowadays, because of JS, people even say "array", which makes me groan because Python's <a href="https://docs.python.org/3/library/array.html">array</a>s are a completely different thing). This way, I think the easiest route would be to just convert the input iterable to a list first. BTW "something coming out of yield" is <a href="https://www.memesmonkey.com/images/memesmonkey/83/832d84b3687340543c2034fdffa29e33.jpeg">called</a> a generator. ;-)

natter1 on April 5, 2021, 4:51 a.m.
<pre class='brush: python'>index_dict = {} pos = 0 for item in items: if item not in index_dict.keys(): index_dict[item] = pos pos += 1 </pre> Argh, I created my own index - converting to list would have been so much easier ^^ But I'm relieved that my concerns weren't completly wrong (many answers here used index() - makes sence if the description was changed later).

veky on April 5, 2021, 4:56 a.m.
... hm, wouldn't it be nice if this were a list ... but it isn't. universe 1: dang, now I have to reimplement what I need from scratch! universe 2: I wonder if there's any way I could convert it to a list? :-D <hr /> Your solution inspired me to go full bureaucratic on this one. The result isn't even that bad. Here, take a <a href="https://py.checkio.org/mission/sort-array-by-element-frequency/publications/veky/python-3/oh-you-mean-an-_iterable_/">look</a>. :-)

HannaAA17 on Dec. 8, 2021, 7:58 p.m.
Hello sir, First of all, thanks a lot for the brilliant codes that you share with us. I'm starting to follow your style and this is the second time I write the same code you write, which made me so happy. I will continue solving these challenges hoping I learn more from you, Thanks.

List, list and list again

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