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Practicals

Python Theory

Sets:

  • Set is a collection just like a list or dictionary.
  • A set is an unordered collection of items, no duplicate entries are present and must be immutable (cannot be changed).
  • Dictionary in python is declared inside curly brackets.Sets can also be used to perform mathematical operations like unions,intersection,symmetric difference,etc.

    • Creating Python Sets:

    A set is created by inside curly braces {}, separated by comma, or by using the built-in set() function.

    Example
    # Make set from a list

    set3 = set([1,2,3,2])
    print(set3)

    # Set and Dictionary while creating empty set

    # Initialize a with {}
    a = {}
    print(type(a))

    a = set()
    print(type(a))
    Output
    SkillPundit: Python-Dictionary Methods
    Example
    # Different types of sets in Python
    # set of integers
    set3 = {1,2,3}
    print(set)

    # Set of mixed datatypes

    set1 = {1.0, "Hello", (1,2,3)}
    print(set1)

    # set cannot have duplicates
    set2 = {1,2,3,4,3,2}
    print(set2)
    Output
    SkillPundit: Python-Dictionary Methods

    Modify sets in python:

    We can add a single element using add() method, and multiple elements using the update() method.

    MethodDescription
    add()Add a single element using add() method.
    update()Multiple elements using the update() method.
    discard()
  • This operation removes element from the set.
  • if an element does not exist, it raises a key error.
    • remove()
  • This operation removes elements from the set.
  • if element does not exist, it does not raise a key error.
    • pop()Remove the last element in the set.
    clear()The clear() method empties the set
    Example
    #Adding Elements to the set
    set = {1,2}
    set.add(3)
    print(set)

    #Update Elements to the set
    set.update([4,5,6])
    print(set)
    Output
    SkillPundit: Python-Dictionary Methods
    Example
    #discard() and remove()
    #initialize my_set
    my_set={1,3,4,5,6}
    print(my_set)

    #discard() an element
    my_set.discard(5)
    print(my_set)

    #remove an element
    my_set.remove(6)
    print(my_set)
    Output
    SkillPundit: Python-Sets Methods
    Example
    #initialize my_set
    set = set("skillpundit")
    print(set)

    #pop an element
    # output : random element
    print(set.pop())

    #clear my_set
    set.clear()
    print(set)
    Output
    SkillPundit: Python-Sets Method

    Loop sets:

    Iterating Through a set :
  • Iterate through each item in a set using a for loop
    • Example
    set = {"apple", "banana", "cherry"}
    for X in set: print(X)
    Output
    SkillPundit: Python-Sets Loops