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1. Top results related to what is a set in python

   • What is the order of elements in a Python set?

     Top Answer

     Answered May 23, 2017 · 7 votes

     You cannot have order in sets. and there is no way to tell how Python orders it. Check this answer for alternatives.

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     1/5

   • What is the fastest way to scan a set of URLs in Python?

     Top Answer

     Answered Jul 19, 2012 · 1 votes

     Yes there is.

     • Use multiple threads all checking different URLs at the same time.
     • Use raw sockets implementing a simple HTTP request. As soon as you get the 200 response (or any other code) you close the connection, avoiding unnecessary transfer of data.

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     2/5

   • What is the best way to set a fallback value in Python?

     Top Answer

     Answered Aug 31, 2012 · 3 votes

     I think of the three options you present, the first one, i.e., the one you are using, is the best. The code is clear and everyone will know what's happening. I can't think of a neater/tidier way, this is how I would code it too, based on the "Simple is better than complex." principle

     Re "I can't help but feel that setting the value and then changing it is a little messy," if you want a default value, there's no way around setting one.

     It certainly is much tidier than using the other two else approaches. Readability counts.

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     3/5

   • What is the preferred way to compose a set from multiple lists in Python

     Top Answer

     Answered Sep 09, 2015 · 13 votes

     For small lists, set(A + B + C) works fine. For larger lists, the following is more efficient because it does not create a temporary list:

     myset = set(A)myset.update(B)myset.update(C)-

     A different approach uses itertools.chain, which is also efficient because it does not create temporary list:

     import itertoolsmyset = set(itertools.chain(A, B, C))-

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     4/5

   • Is there a faster way to check if a value is in a set in python?

     Top Answer

     Answered Nov 02, 2012 · 1 votes

     I am sure you already got your answer, this is for the sake of completeness. Out of curiosity I ran the tests for the methods mentioned I got following results.

     Size=size of main list setopttime: the one that uses s1&s2 setintersectiontime: the one using intersection operation bruteforcetime:burte force time

     Size=1000 setoptime:0:00:00.001000 setintersectiontime:0:00:00.001000 bruteforcetime:0:00:00.005000

     Size=10000 setoptime:0:00:00.001000 setintersectiontime:0:00:00.010000 bruteforcetime:0:00:00.367000

     Size=100000 setoptime:0:00:00.001000 setintersectiontime:0:00:00.115000 bruteforcetime:0:00:35.444000

     Method 1 (setopttime) wins hands down. Here is the code if you want to check.

     import timeitimport datetimedef getList(size): s=[] for i in range(size): s.append(str(i)) return sdef getSubList(size): s=[] for i in range(size/2): s.append(str(i)) return sdef testSet(size): s=set(getList(size)) sublist=set(getSubList(size)) list(s&sublist)def testIntersection(size): s=set(getList(size)) sublist=set(getSubList(size)) list(s.intersection(sublist))def bruteForce(size): s=getList(size) sublist=getSubList(size) final=[] for elem in sublist: try: if s.index(elem)!=-1: final.append(elem) except ValueError: passcurrentsize=1000for i in range(3): t1=datetime.datetime.now() testSet(1000) t2=datetime.datetime.now() testIntersection(currentsize) t3=datetime.datetime.now() bruteForce(currentsize) t4=datetime.datetime.now() print "Size="+str(currentsize) print "setoptime:"+str(t2-t1) print "setintersectiontime:"+str(t3-t2) print "bruteforcetime:"+str(t4-t3) currentsize=currentsize*10

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     5/5

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2. www.w3schools.com › python › python_setsPython Sets - W3Schools

   www.w3schools.com › python › python_sets

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   Set. Sets are used to store multiple items in a single variable. 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. A set is a collection which is unordered, unchangeable*, and unindexed. * Note: Set items are unchangeable, but you ...

3. realpython.com › python-setsSets in Python – Real Python

   realpython.com › python-sets

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   Defining a Set. Python’s built-in set type has the following characteristics: Sets are unordered. Set elements are unique. Duplicate elements are not allowed. A set itself may be modified, but the elements contained in the set must be of an immutable type. Let’s see what all that means, and how you can work with sets in Python.

4. www.programiz.com › python-programming › setPython Set (With Examples) - Programiz

   www.programiz.com › python-programming › set

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   • Create a Set in Python. In Python, we create sets by placing all the elements inside curly braces {}, separated by commas. A set can have any number of items and they may be of different types (integer, float, tuple, string, etc.).
   • Create an Empty Set in Python. Creating an empty set is a bit tricky. Empty curly braces {} will make an empty dictionary in Python. To make a set without any elements, we use the set() function without any argument.
   • Duplicate Items in a Set. Let's see what will happen if we try to include duplicate items in a set. numbers = {2, 4, 6, 6, 2, 8} print(numbers) # {8, 2, 4, 6}
   • Add and Update Set Items in Python. Sets are mutable. However, since they are unordered, indexing has no meaning. We cannot access or change an element of a set using indexing or slicing.

5. People also ask

   What is a set in Python?

   • 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. A set is a collection which is unordered, unchangeable*, and unindexed. * Note: Set items are unchangeable, but you can remove items and add new items.

   Python Sets - W3Schools

   www.w3schools.com/python/python_sets.asp

   See all results for this question

   What is a set type in Python?

   • Python’s built-in set type has the following characteristics: Sets are unordered. Set elements are unique. Duplicate elements are not allowed. A set itself may be modified, but the elements contained in the set must be of an immutable type. Let’s see what all that means, and how you can work with sets in Python. A set can be created in two ways.

   Sets in Python – Real Python

   realpython.com/python-sets/

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   What are elements in a set in Python?

   • Elements in a set are unique. A set doesn’t allow duplicate elements. Elements in a set cannot be changed. For example, they can be numbers, strings, and tuples, but cannot be lists or dictionaries. To define a set in Python, you use the curly brace {}.

   A Basic Guide to the Python Set By Practical Examples

   www.pythontutorial.net/python-basics/python-set/

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   How to create a set in Python?

   • For instance, if we need to store information about student IDs, a set is suitable since student IDs cannot have duplicates. In Python, we create sets by placing all the elements inside curly braces {}, separated by commas. A set can have any number of items and they may be of different types (integer, float, tuple, string, etc.).

   Python Set (With Examples) - Programiz

   www.programiz.com/python-programming/set

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6. www.geeksforgeeks.org › sets-in-pythonSets in Python - GeeksforGeeks

   www.geeksforgeeks.org › sets-in-python

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   May 18, 2023 · A Set in Python programming is an unordered collection data type that is iterable, mutable and has no duplicate elements. Set are represented by { } (values enclosed in curly braces) The major advantage of using a set, as opposed to a list , is that it has a highly optimized method for checking whether a specific element is contained in the set.

7. python.land › python-data-types › python-setPython Set: The Why And How With Example Code

   python.land › python-data-types › python-set

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   Jun 27, 2023 · A Python set is a collection of distinct elements. The set has some things in common with Python lists and tuples, but there are important differences: A Python set can only contain unique values. Sets are unordered. More formally: sets are unordered collections of distinct objects. In this article, we’ll closely examine sets and how to use them.

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8. learnpython.com › blog › python-setsAn In-Depth Guide to Working with Python Sets

   learnpython.com › blog › python-sets

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   Sep 4, 2023 · In a nutshell, sets in Python are a mutable collection of unordered, unique immutable elements. Here’s what each of these attributes mean: Being mutable means that Python sets are changeable and do not have a fixed size: you can add and remove elements from a single set.

9. www.pythontutorial.net › python-basics › python-setA Basic Guide to the Python Set By Practical Examples

   www.pythontutorial.net › python-basics › python-set

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   A Python set is an unordered list of immutable elements. It means: Elements in a set are unordered. Elements in a set are unique. A set doesn’t allow duplicate elements. Elements in a set cannot be changed. For example, they can be numbers, strings, and tuples, but cannot be lists or dictionaries.