python sort key - Brave Search

trying to understand sort(key = ...) function

stackoverflow.com › questions › 62639926 › trying-to-understand-sortkey-function

First, you have to put names in quotes, otherwise it's illegal in python.

Then maybe this will make it easier to understand:

>>> employees = [
...     {'Name': 'Allan', 'Age': 25, 'Salary': 10000},
...     {'Name': 'Sharon', 'Age': 30, 'Salary': 8000},
...     {'Name': 'John', 'Age': 18, 'Salary': 1000} 
... ]
>>> 
>>> sorted( employees, key = lambda x : x['Name'] )
[
    {'Salary': 10000, 'Age': 25, 'Name': 'Allan'},
    {'Salary': 1000, 'Age': 18, 'Name': 'John'},
    {'Salary': 8000, 'Age': 30, 'Name': 'Sharon'}
]

Make note, I don't use any external function, just the lambda, which has no name, just a single parameter (x in our case), that's one of the items on your list, and it returns the key according to which the list will be sorted. You may try to return x['Salary'] or x['Age'] and see the result. The name get_name is quite accidental and has absolutely no influence. Things are actually much easier with lambdas.

Answer from lenik on Stack Overflow

Python documentation

docs.python.org › 3 › howto › sorting.html

Sorting Techniques — Python 3.14.6 documentation

The key function patterns shown above are very common, so Python provides convenience functions to make accessor functions easier and faster. The operator module has itemgetter(), attrgetter(), and a methodcaller() function. Using those functions, the above examples become simpler and faster: >>> from operator import itemgetter, attrgetter >>> sorted(student_tuples, key=itemgetter(2)) [('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)] >>> sorted(student_objects, key=attrgetter('age')) [('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]

stackoverflow.com › questions › 62639926 › trying-to-understand-sortkey-function

python - trying to understand sort(key = ...) function - Stack Overflow

First, you have to put names in quotes, otherwise it's illegal in python.

Then maybe this will make it easier to understand:

>>> employees = [
...     {'Name': 'Allan', 'Age': 25, 'Salary': 10000},
...     {'Name': 'Sharon', 'Age': 30, 'Salary': 8000},
...     {'Name': 'John', 'Age': 18, 'Salary': 1000} 
... ]
>>> 
>>> sorted( employees, key = lambda x : x['Name'] )
[
    {'Salary': 10000, 'Age': 25, 'Name': 'Allan'},
    {'Salary': 1000, 'Age': 18, 'Name': 'John'},
    {'Salary': 8000, 'Age': 30, 'Name': 'Sharon'}
]

Make note, I don't use any external function, just the lambda, which has no name, just a single parameter (x in our case), that's one of the items on your list, and it returns the key according to which the list will be sorted. You may try to return x['Salary'] or x['Age'] and see the result. The name get_name is quite accidental and has absolutely no influence. Things are actually much easier with lambdas.

sort defines what it will do with key. sort expects key to be a callable (i.e. function), which it will call and pass one element of the list to it. sort will call key for each element in the list. The function that you pass (get_name) must match this definition, not the other way around.

employee in def get_name(employee) is an arbitrary parameter name. You define the function, you can name your parameters anything you want.

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reddit.com › r/learnpython › what is the use of the `key` argument in the sort() function?

r/learnpython on Reddit: What is the use of the `key` argument in the sort() function?

June 26, 2022 -

Hi there, I was learning about the lambda/anonymous functions. And I came across this example which sorts a list:

lst = ["Mouse Keyboard", "Router Hub", "CPU UPS"]
lst.sort(key = lambda each: each.split(" ")[-1].lower())
print(lst)

# Which returns output:-
# ['Router Hub', 'Mouse Keyboard', 'CPU UPS']

I tried to google this but was not successful enough. If someone kindly enlightens me on what the key in the sort() function is for. With the google search, I concluded that it takes a function as input. So, the input here will be the 2nd word of each item in the list. But I'm unable to figure out how the sorting function is performed.

The key parameter lets you provide a function to be used to transform the data in your list however you want before sorting. Say you have a list of numbers that you want to sort. But you don't want to sort them the default way (smallest to largest), you want to sort by absolute value. So for example,[4, -5, 3] -> [3, 4, -5]. So in this case, you'd do something like nums = [4, -5, 3] nums.sort(key=abs) What's happening here is that the sort method goes through each number one by one, applies the function and then sorts based on the return value from that function. Another example would be sorting a list of strings by their length. strings = ["Hello", "world", "it's", "a", "me", "Mario!"] strings.sort(key=len) If there isn't a built-in function, you can write your own. For example, if you want to sort a list of tuples by their second argument, you just need to write a function that takes a tuple and returns its second argument. def second(tup): return tup[1] tuples = [("Jake", 167), ("Farid", 845), ("Paula", 443)] tuples.sort(key=second) But if you're only using the function in this one place, often times programmers prefer to use a lambda function instead to keep the clutter to a minimum. tuples = [("Jake", 167), ("Farid", 845), ("Paula", 443)] tuples.sort(key=lambda tup: tup[1])

geeksforgeeks.org › python › python-sorted-function

Python sorted() Function - GeeksforGeeks

December 20, 2025 - Explanation: key=lambda x: x['score'] specifies that the sorting should be done using the 'score' value from each dictionary · Python Sort() Method · Sort Python Dictionaries By Key or Value · How to Sort a Set of Values?

geeksforgeeks.org › python › python-sort-python-dictionaries-by-key-or-value

Sort Python Dictionary by Key or Value - Python - GeeksforGeeks

Given a dictionary in Python, the task is to sort it by key or value, either in ascending or descending order.

Published January 13, 2026

developers.google.com › google for education › python › python sorting

Python Sorting | Python Education | Google for Developers

The sorted() function can accept a reverse=True argument to sort in descending order. Custom sorting can be achieved using the key= argument with sorted(), specifying a function to determine the sorting value for each element.

johngrant.medium.com › python-list-sorting-keys-lambdas-1903b2a4c949

Python — List Sorting, Keys & Lambdas | by John Grant | Medium

July 22, 2016 - “both list.sort() and sorted() ... prior to making comparisons. The value of the key parameter should be a function that takes a single argument and returns a key to use for sorting purposes....

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w3schools.com › python › ref_list_sort.asp

Python List sort() Method

Python Examples Python Compiler Python Exercises Python Quiz Python Challenges Python Practice Problems Python Server Python Syllabus Python Study Plan Python Interview Q&A Python Bootcamp Python Training ... The sort() method sorts the list ascending by default. You can also make a function to decide the sorting criteria(s). ... # A function that returns the length of the value: def myFunc(e): return len(e) cars = ['Ford', 'Mitsubishi', 'BMW', 'VW'] cars.sort(key=myFunc) Try it Yourself »

mimo.org › glossary › python › list-sort()

Python List sort(): Master Data Sorting | Learn Now

Use reverse=True for Descending Order: To sort from highest to lowest, pass the reverse=True argument to the method. Use key for Custom Logic: The key parameter accepts a function (often a lambda) that tells .sort() what to sort by.

programiz.com › python-programming › methods › built-in › sorted

Python sorted()

The sorted() method sorts the elements of the given iterable in ascending order and returns it. In this tutorial, we will learn about the Python sorted() function with the help of examples.

codecademy.com › article › how-to-sort-a-dictionary-by-key-or-value-in-python

How to Sort a Dictionary by Key or Value in Python | Codecademy

When applied to a dictionary’s items, it enables sorting by values in ascending or descending order. The syntax for the sorted() function is: ... key (optional): A function that defines the sorting criterion.

realpython.com › sort-python-dictionary

Sorting a Python Dictionary: Values, Keys, and More – Real Python

December 14, 2024 - To sort a Python dictionary by its keys, you use the sorted() function combined with .items(). This approach returns a list of tuples sorted by keys, which you can convert back to a dictionary using the dict() constructor.

ducatindia.com › blog › difference-between-sort-and-sorted-in-python

What is the Difference Between sort() and sorted() in Python

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Example1: Using sorted() function with List in Python ... The key difference between sort() and sorted() is their return value. Sort () returns nothing because it changes the original list in place. This institute is very nice. I am a student of MERN Full Stack. Nitin Sir is an excellent Trainer, and Nitin Sir is also an excellent Trainer for frontend. The Placement team is also very supportive in helping students get better job opportunities

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cs.stanford.edu › people › nick › py › python-sort.html

When calling sorted, pass in key=by_len.

freecodecamp.org › news › python-sort-dictionary-by-key

Python Sort Dictionary by Key – How to Sort a Dict with Keys

May 25, 2023 - The key must be unique within the dictionary, meaning that no two keys can have the same value. The simplest way to sort a dictionary by its keys is by using the sorted() function along with the items() method of the dictionary.

linkedin.com › learning › python-standard-library-essential-training-26943487 › sorting-with-the-key-parameter

Sorting with the key parameter - Python Tutorial

September 29, 2025 - We cannot provide a description for this page right now

Python documentation

docs.python.org › 3 › tutorial › datastructures.html

5. Data Structures — Python 3.14.6 documentation

Performing list(d) on a dictionary returns a list of all the keys used in the dictionary, in insertion order (if you want it sorted, just use sorted(d) instead).

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How to Use the key Argument in Python (sorted, max, etc.) | note.nkmk.me

August 13, 2023 - The function specified for the key argument is used only for comparison; the actual elements in the result remain unchanged. If you want to modify list elements directly using a function, consider employing list comprehensions. ... The same applies to the sort() method of lists. Sort a list, string, tuple in Python (sort, sorted)

unstop.com › home › blog › python list sort() method | all use cases (+code examples)

Python List sort() Method | All Use Cases (+Code Examples)

February 3, 2025 - The Python list sort() method sorts lists in place using the key and reverse parameters, enabling flexible ordering and custom sorting for various scenarios.

codecademy.com › article › how-to-sort-a-list-in-python

How to sort a list in Python | Codecademy

Python offers two built-in sorting methods: .sort() (modifies the original list) and sorted() (returns a new sorted list). The key parameter allows customization of sorting behavior using lambda functions, named functions, or the operator module.