How to find N-Largest and N-Smallest Numbers in Python!

Quick Python tip how to efficiently find the n largest or smallest numbers of a List.

A note from the official docs: "The latter two functions perform best for smaller values of n. For larger values, it is more efficient to use the sorted() function. Also, when n==1, it is more efficient to use the built-in min() and max() functions. If repeated usage of these functions is required, consider turning the iterable into an actual heap."

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#Python #shorts

[obo]

Python tutorials be like:
Ohh so you wanna *do something* ? Just import the *dosomething* library and that's all, easy right?

[roulio]

def min(list, n): return sorted(list)[:n]
def max(list, n): return sorted(list)[::-1][:n]

Write your fonctions youself, do not import useless modules that you do not understand

[tentaklaus]

Your subscribers help make this one of my favourite channels! Keep up the great work.

[asadqureshi]

Another interesting function.
If you want to know how many times every number or word occur, you can do.
e.g
from collections import Counter
a = [1, 2, 1, 3, 2, 1, 2, 3, 1, 4, 5, 3, 5, 1, 2]

print(Counter(a))

It will give:
Counter({1: 5, 2: 4, 3: 3, 5: 2, 4: 1})

Here the result has given 5 instances of 1 and 4 instances of 2 and so on.

Counter is a dictionary subclass. All dictionary methods can be used in it.
Here elements are keys and count of these elements is value.
Just wanted to share.

[Finkelfunk]

I read that as "How to find the n-word in python" as was mildly concerned for your channel

[NoProblem]

There’s always candidates telling me because we call a built in function, the time complexity is O(1)…

[manojm]

I have been using your tips in my codes these are so good. Thank you for the tips

[nicolasvillagranprieto]

It is much better in terms of complexity to use the build-in function of Python for sorting (Tim sort algorithm) approx. O(nlog(n)) and checking for the number of mins or maxS at the beginning or end of the vector respectively.

[NaveenKumar-vxtk]

Indexing on sorted list will works aswell

[Yutaro-Yoshii]

Edit: Turns out I misunderstood the problem statement. I thought they were just trying to get the smallest in a list. They were trying to get n-smallest. Then I agree that using min/max heap would be a good idea!

Old comment:
-I think this is a bad tip. heap queue creates unnecessary memory overhead. if you just want to know the min/max, simple loop function should be a way to go.
you want to pick your data structures based on your needs, like if you are frequently adding/removing things from a set and want to know min/max at any given time, then heap queue should be a way to go.-

[slumz]

The reason why i failed at coding is what reason would we have to use something like this for?

[Imboredas]

How to use this channel:

1. Check the title
2. Pause the video
3. Get the correct answer in the comments and leave

[wissenistmacht]

How about
Thats what i would do. Requires pandas but is faster i guess. I think Pandas knows evryone and is therefore best suited.

[niuniujunwashere]

No one seems to have mentioned collections.Counter class? That's what I immediately came up off the top of my head and IMO it should be the most useful in most cases :/

Counter accounts for duplicate elements (given that they are hashable, which integers are) and nlargest() and nsmallest() don't really handle those (they're basically equivalent to sorted(reverse=True)[:n] and sorted()[:n] according to the documentation). Say if you have a counter object `c`, then you can use sorted(c)[-n:] or sorted(c)[:n] to obtain the n-largest or n-smallest elements. On top of that if you need the number of occurrences too you can just change `c` into `c.items()`; the item in the sorted list would then be a tuple (element, count)

If you don't care about the count then of course sorted(set(some_list))[-n:] and sorted(set(some_list))[n:] would be more efficient. (No imports!)

(Also I believe heapq.nlargest() and heapq.nsmallest() are just _functions_, not _methods_; the dot notation isn't specific to methods)

[scanticmediatv]

Anything is possible in python as long as the first line has import 😁

[seventeeen]

Top python tip: don't do anything this guy says, just use sorted()[:n]. Its more readable, doesn't require an import, if n is large it's more efficient and if n is small then performance gain is negligible

[hamdhyharoon]

Hey can I know what color theme you are using pls

[dylanprice]

Ok but now how do you "actually" do it

[CaptainLian]

Any advice on doing it on a list of dictionaries? And getting the whole dictionary object itself and not just the largest number?

[korngsamnang]

It's very useful. What is font name?