Use len(), e.g.
>>> l = [1,2,3,4,5,6,7]
>>> print len(l)
7
Given the basic nature of your question, I recommend that you read the Python Tutorial.
Answer from mhawke on Stack OverflowGeeksforGeeks
geeksforgeeks.org › python › sets-in-python
Python Sets - GeeksforGeeks
Set is a built-in Python data type used to store a collection of unique items.
Published: August 11, 2026
Reddit
reddit.com › r/learnpython › question about len function and sets
r/learnpython on Reddit: Question about len function and sets
August 4, 2014 -
I don't quite understand how this len() function works when it's applied to something such as this: len({1,2,3,4,5} & {2,5,7}) = 2. And when I change it somethign such as len({1,2,3,4,6} & {2,5,7}) =3
Top answer 1 of 2
5
The intersection of the set {1, 2, 3, 4, 5} and the set {2, 5, 7} is the set {2, 5} which is a set with two members, and the length of a set is the number of members. There's really not anything complicated about it. Are you maybe confused about the set intersection operation?
2 of 2
1
len({1,2,3,4,6} & {2,5,7}) is not 3. len returns the length of something. If you are confused why len(something) is 2, try printing the something.
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GeeksforGeeks
geeksforgeeks.org › python › python-string-length-len
Python string length - GeeksforGeeks
October 15, 2024 - The len() method is used to find the length of an object in Python. By using len(), we can find the length of strings and lists.
YouTube
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Python Programming 7 - Length of List with len - YouTube
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Published: May 24, 2020
Top answer 1 of 4
5
Use len(), e.g.
>>> l = [1,2,3,4,5,6,7]
>>> print len(l)
7
Given the basic nature of your question, I recommend that you read the Python Tutorial.
2 of 4
3
Use the len function :
len([1,2,3,4,5,6,7])
If you want to learn more about the len function : http://www.tutorialspoint.com/python/list_len.htm
W3Schools
w3schools.com › python › gloss_python_set_length.asp
Python Get the Length of a Set
Python Examples Python Compiler ... Python Interview Q&A Python Training ... To determine how many items a set has, use the len() method....
GeeksforGeeks
geeksforgeeks.org › python › find-the-length-of-a-set-in-python
Find the length of a set in Python - GeeksforGeeks
We are given a set and our task is to find its length. For example, if we have a = {1, 2, 3, 4, 5}, the length of the set should be 5. len() function in Python returns the number of elements in a set.
Published: July 12, 2025
Educative
educative.io › answers › how-to-get-the-length-of-a-set-in-python
How to get the length of a set in Python
The len() function returns the length of the set passed to it.
w3resource
w3resource.com › python-exercises › sets › python-sets-exercise-15.php
Python: Find the length of a set - w3resource
July 5, 2025 - Write a Python program to implement a function that returns the size of a set by converting it to a list and counting. Write a Python program to compare the length of two sets and output the difference in their sizes.
Top answer 1 of 5
28
You don't and do not need to.
Python lists grow and shrink dynamically as needed to fit their contents. Sets are implemented as a hash table, and like Python dictionaries grow and shrink dynamically as needed to fit their contents.
Perhaps you were looking for collections.deque (which takes a maxlen parameter) or something using a heapq (using heapq.heappushpop() when you have reached the maximum) instead?
2 of 5
11
Once you have your list, lst, you can
if len(lst)>10:
lst = lst[:10]
If size more than 10 elements, you truncate to first ten elements.
W3Schools
w3schools.com › PYTHON › python_sets.asp
Python Sets
Set is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Tuple, and Dictionary, all with different qualities and usage.
Instagram
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Python Set Length
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Python
docs.python.org › 3 › builtins › stdtypes.html
Built-in Types — Python 3.15.0 documentation
The following sections describe the standard types that are built into the interpreter. The principal built-in types are numerics, sequences, mappings, classes, instances and exceptions. Some colle...
Quora
quora.com › How-do-I-assign-the-length-for-a-variable-in-Python
How to assign the length for a variable in Python - Quora
Answer (1 of 6): You can’t assign a length to an integer - an integer don’t have a length. A string does - but you can’t assign an ordinary string to be a fixed length. What you can do is validation on your user input [code]def is_number(str): '''Validate that a user inputed string is ...
Real Python
realpython.com › len-python-function
Using the len() Function in Python – Real Python
September 9, 2025 - The len() function in Python is a built-in function that returns the length of an object. It provides the number of items in a container, including sequences like strings, lists, and tuples or collections like dictionaries and sets.
DigitalOcean
digitalocean.com › community › tutorials › find-the-length-of-a-list-in-python
How to find the length of a list in Python | DigitalOcean
How to find the length of a list in Python using the len() function. Includes examples, edge cases, and tips for working with nested or dynamic lists.
GeeksforGeeks
geeksforgeeks.org › python › find-the-size-of-a-set-in-python
Find the size of a Set in Python - GeeksforGeeks
September 10, 2025 - The getsizeof() function from Python’s sys module returns the memory used by an object, including garbage collection overhead. It has been implemented in the below example. Example: We import sys module, create three different sets and then pass each set into sys.getsizeof() to check its memory usage.
Medium
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Medium
April 18, 2026 - I’d been running Gemma 4’s 26B MoE against the same coding prompt I use to stress-test every new model — build a Python REST endpoint with rate limiting, a retry queue, and graceful shutdown handling — and the output was actually good. Not “good for a local model” good.
Hyperskill
hyperskill.org › university › python › set-and-set-in-python
Python set(): Create Sets, Add, Remove & Compare Elements
June 5, 2026 - Difference: Find elements in one set but not in another. ... In Python, a set is a built-in data structure used to store a collection of unique items. It is mutable, meaning its elements can be modified, added, or removed.