Python offers a rich collection of sequence object types, and sets are one of them.

Python sets are unordered collections of unique elements and immutable objects. You can think of them as a dictionary with just the keys and its values thrown away. Therefore, each item of a set should be unique. Alright! Here are simple programs based on sets that will help you get started with sets in Python.

Remember to tackle these questions on your own before checking for solutions!

__Find the Differences Between Two Lists Using Sets____Check if a Given String Is Heterogram or Not____Find Maximum and Minimum Values of a Set____Get All the Subsets of a Given Size in a Set____Determine if Two Sets Are Disjoint or Not Without In-built Methods____Remove the Given Items of a Set at Once____Count Number of Vowels in a Given String Using Sets____Convert a Set to String____Find Common Elements of Three Given Lists Using Sets____Square the Elements of Set Using for Loop____Check if a Set Is Superset Itself or Another Given Set____Perform Intersection of Two Lists Using Set Methods____Check if a Given Value Is Present in the Set or Not__

**Program in Python to Find the Differences Between Two Lists Using Sets**

There are multiple ways to find the differences between two given sets. One way is using sets and their methods.

**Input:**

List1 = [10, 45, 34, 20, 11]

List2 = [11, 25, 45, 20]

**Output:**

[10, 34, 25]

In this example, we are first converting the two lists and using the ‘-’ operator to find the difference between them. Alternatively, you can also difference the () method to do the same. Then you can apply list() to convert the dictionaries to list.

#difference between two lists- Using set()def diff_between(list1, list2): A = set(list1) B = set(list2) #return list(A - B) + list(B - A) return list({*A.difference(B),*B.difference(A)})# Driver CodeList1 = [10, 45, 34, 20, 11]List2 = [11, 25, 45, 20]print(diff_between(List1, List2))

**Python Program to Check if a Given String Is Heterogram or Not**

A string is a heterogram if it has no alphabet that occurs more than once. For example, “NaukriLearning” is not a heterogram. However, “abc def ghi jkl” is a heterogram. You can follow the below steps to check if a given string is a heterogram or not.

- Separate all the alphabets from other any other characters (using list comprehension)
- Convert list of alphabets into set because set has unique elements (using set())
- Check if the length of the set is equal to number of alphabets
- If yes, then string is heterogram otherwise its not

Here’s the code! We are using the ord() function which returns the ASCII value. If the ASCII value of the alphabet is greater than or equal to that of ‘a’ and less than or equal to ‘z’ then add it to the list ‘alphabets’

#check if string is heterogram or not #sample stringstr1 = "Naurkrilearning"str2 = "abcd efgh ijkl"def check_heterogram(input): # separate out list of all alphabets list_of_alphabets = [ alph for alph in input if ( ord(alph) >= ord('a') and ord(alph) <= ord('z') )] # convert into set and compare lengths if len(set(list_of_alphabets))==len(list_of_alphabets): print ("Yes, the string '", input, "'is heterogram") else: print ("No, the string'", input, "'is not heterogram") check_heterogram(str1)check_heterogram(str2)

**Program in Python to Print Maximum and Minimum Elements**

You can use min() and max() functions to achieve this.

#find max and min values #initializing setset1 = {15, 25, 2, 10, 11, 55} print("Original set elements:", set1)print("Maximum value of given set:", max(set1))print("Minimum value of given set:", min(set1))

**Python Program to Get All the Subsets of a Given Size in a Set**

You can do this in a Pythonic way using loops. However, in this example, let us try to execute it differently. Python has a method called itertools.combinations(iterable, n), which returns n length subsequences of a given iterable.

Here’s the code! In the below code, use itertools.combinations(setn, n) in for loop and then append the resultant sets to the list

#get all subset of give size in a set#importing module itertool which has combinations() methodimport itertools #initializing set and length of sunsetset1 = {1, 2, 3}n = 2 def get_subsets(setn, n): return [set(i) for i in itertools.combinations(setn, n)] print(get_subsets(set1, n))

Try executing this by not using any python built-in module. Using loops and creating functions.

**Python Program to Determine if Two Sets Are Disjoint or Not Without Using Inbuilt-in Functions**

Sets A and B are called disjoint if they do not have any common elements. You can check if two given sets are disjoint or not in multiple ways. In this example, let’s try implementing it without any in-built functions.

#Determine if two sets are disjoint or not# take each item of set1 and search if it is present in set2 # if yes return False def check_if_disjoint(set1, set2): counter = 0 # separate out list of all alphabets for x in set1: if x in set2: counter = counter + 1 if counter > 0: return False else: return True #initializing setsset1 = {'Python', 'Java', 'Data Science'}set2 = {'ML', 'AI', 'R Language', 'Python'}set3 = {'Data Analytics', 'Robotics', 'Deep Learning'} #printing resultsprint("Are set1 and set2 disjoint? :", check_if_disjoint(set1, set2))print("Are set1 and set3 disjoint? :", check_if_disjoint(set1, set3))

**Program in Python to Remove the Given Items of a Set at Once**

You can remove all the elements of a set at once using the clear() method. However, what we really want to do here is remove only the given elements but at once. To do so you can use the set method difference_update(), which will find the uncommon elements of set1 and the set of items to be removed and then update the set1, which is called as the difference_update() method.

#removing the given items a onceset1 = {0, 1, 2, 3, 4, 5, 6}print("Original set1:", set1) #use difference_update() methodset1.difference_update({2, 3, 6}) print("Result set1:", set1)

**Python Program to Count Number of Vowels in a Given String Using Sets**

You need to write a program that will count the number of vowels in a given string.

#count number of vowels def count_vowels(str1): #create a set with vowels (both uppercase & lowercase) vowels = set('aeiouAEIOU') counter = 0 #check if the each character if string is vowel #if yes increment the counter for ch in str1: if ch in vowels: counter = counter + 1 #print the count print("Number of Vowels in Given String = ", counter) #driver codestring1 = "Shiksha Online"count_vowels(string1)

**Program in Python to Convert a Set to String**

Let’s do this using the str() method, or join() method as shown below.

#Convert a Set to Stringprint("Converting set to string")#Initializing setvar1 = {'a', 'e', 'i', 'o', 'u'}print("The datatype of var1 : " + str(type(var1)))print("Contents of var1 : ", var1) # convert a Set to String using strvar2 = str(var1)print("\nThe data type of var2 : " + str(type(var2)))print("Contents of var2 : " + var2) # convert a Set to String using joinvar3 = ', '.join(var1)print("\nThe datatype of s : " + str(type(var3)))print("Contents of s : ", var3)

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**Program in Python to Find Common Elements of Three Given Lists Using Sets**

You can check this by performing the intersection operation as shown below.

#find the common elements in three lists def find_common(list1, list2, list3): set1 = set(list1) set2 = set(list2) set3 = set(list3) #first perform intersection on set1 & set2 res_set1 = set1.intersection(set2) #perform intersection of res_set1 & set3 res_set2 = res_set1.intersection(set3) #converting to list #printing the result end_list = list(res_set2) print(end_list) # Driver CodeList1 = [10, 45, 34, 20, 11]List2 = [11, 25, 45, 20]List3 = [20, 25, 11, 14, 45, 65] find_common(List1,List2, List3)

**Python Program To Square the Elements of Set Using for Loop**

The solutions demonstrate how you can iterate through the items of set and square them using loop as well as set comprehensions.

#Square elements of set#Traversing a setset1 = {0, 1, 2, 3, 4}print("Original set1:", set1) #square the elements of set using for loop res_set = set()for x in set1: res_set.add(x*x)print("Updated copy of set1:", res_set) #using set comprehensionprint("Iterating set through set comprehension:", {x ** 2 for x in [1, 2, 3, 4]})

**Python Program to Check if a Set Is Superset Itself or Another Given Set**

#check if set is superset of itself or other given set# Initializing setsset1 = {10, 45, 34, 20}set2 = {10, 45, 34, 20, 11}set3 = {20, 25, 11, 14, 45, 65} print("Is set1 superset of itself?:", set1.issuperset(set1))print("Is set2 superset of set1?:", set2.issuperset(set1))print("Is set3 superset of set1?:", set3.issuperset(set1))

**Program in Python to Perform Intersection of Two Lists Using Set Methods**

You can use set methods such as set() and intersection() to perform the intersection of two lists as shown below. The solution also shows how to perform this using & operator.

# Perform intersection of two lists using set() & intersection()def perform_intersection(list1, list2): return set(list1).intersection(set(list2)) def do_intersection(list1, list2): return list(set(list1) & set(list2)) # Driver CodeList1 = [11, 25, 45, 20]List2 = [20, 25, 11, 14, 45, 65] print("Using intersection() method:", list(perform_intersection(List1, List2)))print("Using set(), & operator:", list(do_intersection(List1, List2)))

**Python Program To Check If a Given Value is Present in Set or Not**

You can check for an item in the string using in operator as shown below.

#check if a given item is present in set or notset1 = {10, 45, 34, 20} #original setprint("The original set:", set1) #check if present or not using 'in'print("Is 6 present in set1:", 6 in set1)print("Is 20 present in set1:", 20 in set1)

That’s it, folks! I hope you found these Python programs helpful. If you have any problem statement that you are stuck with please raise a query in the comment section below. Happy coding!

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